Second Primary Breast Cancer in Young Breast Cancer Survivors

Importance

Among women diagnosed with primary breast cancer (BC) at or younger than age 40 years, prior data suggest that their risk of a second primary BC (SPBC) is higher than that of women who are older when they develop a first primary BC.

Objective

To estimate cumulative incidence and characterize risk factors of SPBC among young patients with BC.

Design, Setting, and Participants

Participants were enrolled in the Young Women's Breast Cancer Study, a prospective study of 1297 women aged 40 years or younger who were diagnosed with stage 0 to III BC from August 2006 to June 2015. Demographic, genetic testing, treatment, and outcome data were collected by patient surveys and medical record review. A time-to-event analysis was used to account for competing risks when determining cumulative incidence of SPBC, and Fine-Gray subdistribution hazard models were used to evaluate associations between clinical factors and SPBC risk. Data were analyzed from January to May 2023.

Main Outcomes and Measures

The 5- and 10- year cumulative incidence of SPBC.

Results

In all, 685 women with stage 0 to III BC (mean [SD] age at primary BC diagnosis, 36 [4] years) who underwent unilateral mastectomy or lumpectomy as the primary surgery for BC were included in the analysis. Over a median (IQR) follow-up of 10.0 (7.4-12.1) years, 17 patients (2.5%) developed an SPBC; 2 of these patients had cancer in the ipsilateral breast after lumpectomy. The median (IQR) time from primary BC diagnosis to SPBC was 4.2 (3.3-5.6) years. Among 577 women who underwent genetic testing, the 10-year risk of SPBC was 2.2% for women who did not carry a pathogenic variant (12 of 544) and 8.9% for carriers of a pathogenic variant (3 of 33). In multivariate analyses, the risk of SPBC was higher among PV carriers vs noncarriers (subdistribution hazard ratio [sHR], 5.27; 95% CI, 1.43-19.43) and women with primary in situ BC vs invasive BC (sHR, 5.61; 95% CI, 1.52-20.70).

Conclusions

Findings of this cohort study suggest that young BC survivors without a germline pathogenic variant have a low risk of developing a SPBC in the first 10 years after diagnosis. Findings from germline genetic testing may inform treatment decision-making and follow-up care considerations in this population.

Postpartum Breast Cancer and Survival in Women With Germline BRCA Pathogenic Variants

Importance

In young-onset breast cancer (YOBC), a diagnosis within 5 to 10 years of childbirth is associated with increased mortality. Women with germline BRCA1/2 pathogenic variants (PVs) are more likely to be diagnosed with BC at younger ages, but the impact of childbirth on mortality is unknown.

Objective

To determine whether time between most recent childbirth and BC diagnosis is associated with mortality among patients with YOBC and germline BRCA1/2 PVs.

Design, Setting, and Participants

This prospective cohort study included women with germline BRCA1/2 PVs diagnosed with stage I to III BC at age 45 years or younger between 1950 and 2021 in the United Kingdom, who were followed up until November 2021. Data were analyzed from December 3, 2021, to November 29, 2023.

Exposure

Time between most recent childbirth and subsequent BC diagnosis, with recent childbirth defined as 0 to less than 10 years, further delineated to 0 to less than 5 years and 5 to less than 10 years.

Main Outcomes and Measures

The primary outcome was all-cause mortality, censored at 20 years after YOBC diagnosis. Mortality of nulliparous women was compared with the recent post partum groups and the 10 or more years post partum group. Cox proportional hazards regression analyses were adjusted for age, tumor stage, and further stratified by tumor estrogen receptor (ER) and BRCA gene status.

Results

Among 903 women with BRCA PVs (mean [SD] age at diagnosis, 34.7 [6.1] years; mean [SD] follow-up, 10.8 [9.8] years), 419 received a BC diagnosis 0 to less than 10 years after childbirth, including 228 women diagnosed less than 5 years after childbirth and 191 women diagnosed 5 to less than 10 years after childbirth. Increased all-cause mortality was observed in women diagnosed within 5 to less than 10 years post partum (hazard ratio [HR], 1.56 [95% CI, 1.05-2.30]) compared with nulliparous women and women diagnosed 10 or more years after childbirth, suggesting a transient duration of postpartum risk. Risk of mortality was greater for women with ER-positive BC in the less than 5 years post partum group (HR, 2.35 [95% CI, 1.02-5.42]) and ER-negative BC in the 5 to less than 10 years post partum group (HR, 3.12 [95% CI, 1.22-7.97]) compared with the nulliparous group. Delineated by BRCA1 or BRCA2, mortality in the 5 to less than 10 years post partum group was significantly increased, but only for BRCA1 carriers (HR, 2.03 [95% CI, 1.15-3.58]).

Conclusions and Relevance

These findings suggest that YOBC with germline BRCA PVs was associated with increased risk for all-cause mortality if diagnosed within 10 years after last childbirth, with risk highest for ER-positive BC diagnosed less than 5 years post partum, and for ER-negative BC diagnosed 5 to less than 10 years post partum. BRCA1 carriers were at highest risk for poor prognosis when diagnosed at 5 to less than 10 years post partum. No such associations were observed for BRCA2 carriers. These results should inform genetic counseling, prevention, and treatment strategies for BRCA PV carriers.

Conception and pregnancy among women with a live birth after breast cancer treatment: A survey study of young breast cancer survivors

BACKGROUND

Breast cancer (BC) is the most common malignancy in women of reproductive age. This study sought to explore the postcancer conception and pregnancy experience of young BC survivors to inform counseling.

METHODS

In the Young Women's Breast Cancer Study (NCT01468246), a multicenter, prospective cohort, participants diagnosed at age ≤40 years with stage 0-III BC who reported ≥1 postdiagnosis live birth were sent an investigator-developed survey.

RESULTS

Of 119 eligible women, 94 (79%) completed the survey. Median age at diagnosis was 32 years (range, 17-40) and at first postdiagnosis delivery was 38 years (range, 29-47). Most had stage I or II (77%) and HR+ (78%) BC; 51% were nulligravida at diagnosis. After BC treatment, most (62%) conceived naturally, though 38% used assisted reproductive technology, 74% of whom first attempted natural conception for a median of 9 months (range, 2-48). Among women with a known inherited pathogenic variant (n = 20), two underwent preimplantation genetic testing. Of 59 women on endocrine therapy before pregnancy, 26% did not resume treatment. Hypertensive disorders of pregnancy (20%) was the most common obstetrical condition. Nine percent of newborns required neonatal intensive care unit admission and 9% had low birth weight.

CONCLUSION

Among women with live births after BC treatment, most conceived naturally and having a history of BC did not appear to negatively impact pregnancy complications, though the high rate of hypertensive disorders of pregnancy warrants further investigation. The prolonged period of attempting natural conception for some survivors suggests the potential need for improved understanding and counseling surrounding family planning goals after BC.

Safety and Efficacy of Tucatinib, Letrozole, and Palbociclib in Patients with Previously Treated HR+/HER2+ Breast Cancer

PURPOSE

To overcome resistance to antihormonal and HER2-targeted agents mediated by cyclin D1-CDK4/6 complex, we proposed an oral combination of the HER2 inhibitor tucatinib, aromatase inhibitor letrozole, and CDK4/6 inhibitor palbociclib (TLP combination) for treatment of HR+/HER2+ metastatic breast cancer (MBC).

PATIENTS AND METHODS

Phase Ib/II TLP trial (NCT03054363) enrolled patients with HR+/HER2+ MBC treated with ≥2 HER2-targeted agents. The phase Ib primary endpoint was safety of the regimen evaluated by NCI CTCAE version 4.3. The phase II primary endpoint was efficacy by median progression-free survival (mPFS).

RESULTS

Forty-two women ages 22 to 81 years were enrolled. Patients received a median of two lines of therapy in the metastatic setting, 71.4% had visceral disease, 35.7% had CNS disease. The most common treatment-emergent adverse events (AE) of grade ≥3 were neutropenia (64.3%), leukopenia (23.8%), diarrhea (19.0%), and fatigue (14.3%). Tucatinib increased AUC10-19 hours of palbociclib 1.7-fold, requiring palbociclib dose reduction from 125 to 75 mg daily. In 40 response-evaluable patients, mPFS was 8.4 months, with similar mPFS in non-CNS and CNS cohorts (10.0 months vs. 8.2 months; P = 0.9). Overall response rate was 44.5%, median duration of response was 13.9 months, and clinical benefit rate was 70.4%; 60% of patients were on treatment for ≥6 months, 25% for ≥1 year, and 10% for ≥2 years. In the CNS cohort, 26.6% of patients remained on study for ≥1 year.

CONCLUSIONS

TLP combination was safe and tolerable. AEs were expected and manageable with supportive therapy and dose reductions. TLP showed excellent efficacy for an all-oral chemotherapy-free regimen warranting further testing. See related commentary by Huppert and Rugo, p. 4993.

Genomics of ERBB2-Positive Breast Cancer in Young Women Before and After Exposure to Chemotherapy Plus Trastuzumab

PURPOSE

Erb-B2 receptor tyrosine kinase 2 (ERBB2)-positive breast cancer (BC) is particularly common in young women. Genomic features of ERBB2-positive tumors before and after chemotherapy and trastuzumab (chemo + H) have not been described in young women and are important for guiding study of therapeutic resistance in this population.

METHODS

From a large prospective cohort of women age 40 years or younger with BC, we identified patients with ERBB2-positive BC and tumor tissue available before and after chemo + H. Whole-exome sequencing (WES) was performed on each tumor and on germline DNA from blood. Tumor-normal pairs were analyzed for mutations and copy number (CN) changes.

RESULTS

Twenty-two women had successful WES on samples from at least one time point; 12 of these had paired sequencing results from before and after chemo + H and 10 had successful sequencing from either time point. TP53 was the only significantly recurrently mutated gene in both pre- and post-treatment samples. MYC gene amplification was observed in four post-treatment tumors. Seven of 12 patients with paired samples showed acquired and/or clonally enriched alterations in cancer-related genes. One patient had an increased clonality putative activating mutation in ERBB2. Another patient acquired a clonal hotspot mutation in TP53. Other genomic changes acquired in post-treatment specimens included alterations in NOTCH2, STIL, PIK3CA, and GATA3. There was no significant change in median ERBB2 CN (20.3 v 22.6; Wilcoxon P = .79) between paired samples.

CONCLUSION

ERBB2-positive BCs in young women displayed substantial genomic evolution after treatment with chemo + H. Approximately half of patients with paired samples demonstrated acquired and/or clonally enriched genomic changes in cancer genes. ERBB2 CN changes were uncommon. We identified several genes warranting exploration as potential mechanisms of resistance to therapy in this population.

Phase II trial of fulvestrant plus enzalutamide in ER+/HER2- advanced breast cancer

This clinical trial combined fulvestrant with the anti-androgen enzalutamide in women with metastatic ER+/HER2- breast cancer (BC). Eligible patients were women with ECOG 0-2, ER+/HER2- measurable or evaluable metastatic BC. Prior fulvestrant was allowed. Fulvestrant was administered at 500 mg IM on days 1, 15, 29, and every 4 weeks thereafter. Enzalutamide was given at 160 mg po daily. Fresh tumor biopsies were required at study entry and after 4 weeks of treatment. The primary efficacy endpoint of the trial was the clinical benefit rate at 24 weeks (CBR24). The median age was 61 years (46-87); PS 1 (0-1); median of 4 prior non-hormonal and 3 prior hormonal therapies for metastatic disease. Twelve had prior fulvestrant, and 91% had visceral disease. CBR24 was 25% (7/28 evaluable). Median progression-free survival (PFS) was 8 weeks (95% CI: 2-52). Adverse events were as expected for hormonal therapy. Significant (p < 0.1) univariate relationships existed between PFS and ER%, AR%, and PIK3CA and/or PTEN mutations. Baseline levels of phospho-proteins in the mTOR pathway were more highly expressed in biopsies of patients with shorter PFS. Fulvestrant plus enzalutamide had manageable side effects. The primary endpoint of CBR24 was 25% in heavily pretreated metastatic ER+/HER2- BC. Short PFS was associated with activation of the mTOR pathway, and PIK3CA and/or PTEN mutations were associated with an increased hazard of progression. Thus, a combination of fulvestrant or other SERD plus AKT/PI3K/mTOR inhibitor with or without AR inhibition warrants investigation in second-line endocrine therapy of metastatic ER+ BC.

Interrupting Endocrine Therapy to Attempt Pregnancy after Breast Cancer

BACKGROUND

Prospective data on the risk of recurrence among women with hormone receptor-positive early breast cancer who temporarily discontinue endocrine therapy to attempt pregnancy are lacking.

METHODS

We conducted a single-group trial in which we evaluated the temporary interruption of adjuvant endocrine therapy to attempt pregnancy in young women with previous breast cancer. Eligible women were 42 years of age or younger; had had stage I, II, or III disease; had received adjuvant endocrine therapy for 18 to 30 months; and desired pregnancy. The primary end point was the number of breast cancer events (defined as local, regional, or distant recurrence of invasive breast cancer or new contralateral invasive breast cancer) during follow-up. The primary analysis was planned to be performed after 1600 patient-years of follow-up. The prespecified safety threshold was the occurrence of 46 breast cancer events during this period. Breast cancer outcomes in this treatment-interruption group were compared with those in an external control cohort consisting of women who would have met the entry criteria for the current trial.

RESULTS

Among 516 women, the median age was 37 years, the median time from breast cancer diagnosis to enrollment was 29 months, and 93.4% had stage I or II disease. Among 497 women who were followed for pregnancy status, 368 (74.0%) had at least one pregnancy and 317 (63.8%) had at least one live birth. In total, 365 babies were born. At 1638 patient-years of follow-up (median follow-up, 41 months), 44 patients had a breast cancer event, a result that did not exceed the safety threshold. The 3-year incidence of breast cancer events was 8.9% (95% confidence interval [CI], 6.3 to 11.6) in the treatment-interruption group and 9.2% (95% CI, 7.6 to 10.8) in the control cohort.

CONCLUSIONS

Among select women with previous hormone receptor-positive early breast cancer, temporary interruption of endocrine therapy to attempt pregnancy did not confer a greater short-term risk of breast cancer events, including distant recurrence, than that in the external control cohort. Further follow-up is critical to inform longer-term safety. (Funded by ETOP IBCSG Partners Foundation and others; POSITIVE ClinicalTrials.gov number, NCT02308085.).

Extended adjuvant endocrine therapy in a longitudinal cohort of young breast cancer survivors

Extended adjuvant endocrine therapy (eET) improves outcomes in breast cancer survivors. Most studies however have been limited to postmenopausal women, and optimal eET for young survivors is uncertain. We report eET use among participants in the Young Women's Breast Cancer Study (YWS), a multicenter prospective cohort of women age ≤40 newly diagnosed with breast cancer enrolled between 2006-2016. Women with stage I-III hormone receptor-positive breast cancer, ≥6 years from diagnosis without recurrence were considered eET candidates. Use of eET was elicited from annual surveys sent years 6-8 after diagnosis, censoring for recurrence/death. 663 women were identified as eET candidates with 73.9% (490/663) having surveys eligible for analysis. Among eligible participants, mean age was 35.5 (±3.9), 85.9% were non-Hispanic white, and 59.6% reported eET use. Tamoxifen monotherapy was the most reported eET (77.4%), followed by aromatase inhibitor (AI) monotherapy (21.9%), AI-ovarian function suppression (AI-OFS) (6.8%) and tamoxifen-OFS (3.1%). In multivariable analysis, increasing age (per year odds ratio [OR]: 1.10, 95% confidence interval [CI]: 1.04-1.16), stage (II v. I: OR: 2.86, 95% CI: 1.81-4.51; III v. I: OR: 3.73, 95%CI: 1.87-7.44) and receipt of chemotherapy (OR: 3.66, 95% CI: 2.16-6.21) were significantly associated with eET use. Many young breast cancer survivors receive eET despite limited data regarding utility in this population. While some factors associated with eET use reflect appropriate risk-based care, potential sociodemographic disparities in uptake warrants further investigation in more diverse populations.

Tumor-restrictive type III collagen in the breast cancer microenvironment: prognostic and therapeutic implications

Collagen plays a critical role in regulating breast cancer progression and therapeutic resistance. An improved understanding of both the features and drivers of tumor-permissive and -restrictive collagen matrices are critical to improve prognostication and develop more effective therapeutic strategies. In this study, using a combination of in vitro, in vivo and in silico experiments, we show that type III collagen (Col3) plays a tumor-restrictive role in human breast cancer. We demonstrate that Col3-deficient, human fibroblasts produce tumor-permissive collagen matrices that drive cell proliferation and suppress apoptosis in noninvasive and invasive breast cancer cell lines. In human TNBC biopsy samples, we demonstrate elevated deposition of Col3 relative to type I collagen (Col1) in noninvasive compared to invasive regions. Similarly, in silico analyses of over 1000 breast cancer patient biopsies from The Cancer Genome Atlas BRCA cohort revealed that patients with higher Col3:Col1 bulk tumor expression had improved overall, disease-free and progression-free survival relative to those with higher Col1:Col3 expression. Using an established 3D culture model, we show that Col3 increases spheroid formation and induces formation of lumen-like structures that resemble non-neoplastic mammary acini. Finally, our in vivo study shows co-injection of murine breast cancer cells (4T1) with rhCol3-supplemented hydrogels limits tumor growth and decreases pulmonary metastatic burden compared to controls. Taken together, these data collectively support a tumor-suppressive role for Col3 in human breast cancer and suggest that strategies that increase Col3 may provide a safe and effective modality to limit recurrence in breast cancer patients.

Fertility Preferences and Practices Among Young Women With Breast Cancer: Germline Genetic Carriers Versus Noncarriers

BACKGROUND

Young women with breast cancer who carry germline genetic pathogenic variants may face distinct fertility concerns, yet limited data exist comparing fertility preferences and practices between carriers and noncarriers.

PATIENTS AND METHODS

Participants in the Young Women's Breast Cancer Study (NCT01468246), a prospective cohort of women diagnosed with breast cancer at ≤40 years, who completed a modified Fertility Issues Survey were included in this analysis.

RESULTS

Of 1052 eligible participants, 118 (11%) tested positive for a pathogenic variant. Similar proportions (P = .23) of carriers (46%, [54/118]) and noncarriers (37%, [346/934]) desired more biologic children prediagnosis, and desire decreased similarly postdiagnosis (carriers, 30% [35/118] vs. noncarriers, 26% [244/934], P = .35). Among those desiring children postdiagnosis (n = 279), concern about cancer risk heritability was more common among carriers (74% [26/35] vs. noncarriers, 36% [88/244], P < .01). Carriers were more likely to report that concern about cancer risk heritability contributed to a lack of certainty or interest in future pregnancies (20% [16/81] vs. noncarriers, 7% [49/674], P = .001). Similar proportions (P = .65) of carriers (36% [43/118]) and noncarriers (38% [351/934]) were somewhat or very concerned about infertility post-treatment; utilization of fertility preservation strategies was also similar (carriers, 14% [17/118] vs. noncarriers, 12% [113/934], P = .78).

CONCLUSION

Carriers were similarly concerned about future fertility and as likely to pursue fertility preservation as noncarriers. Concern about cancer risk heritability was more frequent among carriers and impacted decisions not to pursue future pregnancies for some, underscoring the importance of counseling regarding strategies to prevent transmission to offspring, including preimplantation genetic testing.

Abstract P5-08-05: Conception and Pregnancy Among Young Breast Cancer Survivors

Background: Breast cancer (BC) is the most common malignancy among women of reproductive age. Given limited data describing the conception and pregnancy experience of young BC survivors, we sought to explore these outcomes to inform counseling of women interested in future childbearing. Methods: Participants with stage 0-III BC in the Young Women’s Breast Cancer Study (NCT01468246), a multi-center, prospective cohort of women diagnosed at age ≤ 40 from 2006-2016 who reported ≥ 1 live birth from a pregnancy after diagnosis were sent a survey with investigator-developed questions focused on their first post-diagnosis live birth. Women who had been diagnosed with BC during pregnancy were excluded from this analysis. The survey assessed conception, use of assisted reproductive technology (ART), pre-implantation genetic testing (PGT), endocrine therapy (ET), and peripartum complications. Summary statistics are presented. Results: 92/119 eligible women completed the survey (response rate: 77%). Median age at diagnosis was 32 (range:17-40) years and at delivery was 37 (range: 29-47) years. Median time from diagnosis to delivery was 58 months (range: 11-154). Most women had stage 2 BC (43%, 40/92); 68% received chemotherapy (63/92); about half (51%, 47/92) were nulligravida at diagnosis. Overall, 61% of pregnancies were conceived naturally (56/92) and 39% with ART (36/92): 32% by in-vitro fertilization (IVF, 29/92), 7% with fertility medications only (6/92), and 1 with intrauterine insemination. 38% of IVF pregnancies were conceived using products from fertility preservation prior to BC treatment (11/29). Among women who used ART, 74% attempted to conceive naturally (25/36) for a median of 9 (range: 2-48) months prior to pursuing ART. The most common reasons for pursuing ART include infertility following BC treatment (33%, 12/36) and expediting conception to resume treatment (17%, 6/36). 11% of those with known inherited pathologic variant mutations underwent PGT (2/19). Reasons for not pursuing PGT included belief in more effective cancer risk reduction in the future (29%, 5/17), not being offered PGT (24%, 4/17), high cost (12%, 2/17), no interest in IVF (12%, 2/17), acceptable odds for inheriting the mutation (24%, 4/17), and belief in other risk reduction strategies (18%, 3/17); 1 woman reported ethical concerns. Of 57 women who took ET pre-pregnancy (63%), nearly all (96%, 55/57) discontinued ET &gt; 3 months prior to attempting to conceive; 1 discontinued after awareness of pregnancy. Of those who had received prior ET, 60% resumed ET (34/57) a median of 3 (range: 1-50) months after pregnancy. Among 23 women who did not resume, 13 (23%) had completed the recommended duration; the remaining 10 reported one or more of the following reasons: felt better while off (28%, 6/23), desire for another child (22%, 5/23), and desire to breastfeed (17%, 4/23). Median time to delivery was 39 (range: 28-42) weeks with 12% delivering preterm &lt; 37 weeks (11/92). 47% had a Caesarean section (43/92), with prolonged labor the most common indication (33%, 14/43). Hypertensive disorders of pregnancy (HDP, 20%, 18/92), gestational diabetes (7%, 6/92), small for gestational age (7%, 6/92), and postpartum hemorrhage (5%, 5/92) were the most common obstetrical complications. 9% of women had newborns requiring NICU admission (8/92) and 9% had low birth weight (8/92). Conclusion: Among young BC survivors with a live birth following diagnosis, most conceived naturally, with the majority who used ART first attempting natural conception. There was limited use of PGT among mutation carriers with ¼ not having been offered testing. Patient reported peripartum complications appear consistent with population norms, though the relatively higher rate of HDP bears further research. Among those yet to complete their ET, a notable proportion did not resume following delivery. This novel data may help to inform the care of young breast cancer survivors pursuing pregnancy.

Citation Format: Kimia Sorouri, Tal Sella, Shoshana Rosenberg, Margaret Loucks, Kathryn Ruddy, Shari I. Gelber, Rulla M. Tamimi, Jeffrey M. Peppercorn, Lidia Schapira, Virginia F. Borges, Steven E. Come, Ellen Warner, Ann Partridge. Conception and Pregnancy Among Young Breast Cancer Survivors [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-08-05.

Abstract OT3-09-01: Clinical Trial of Alpelisib and Tucatinib in Patients with PIK3CA-Mutant HER2-Positive Metastatic Breast Cancer

Phosphatidylinositol 3-kinase (PI3K) pathway plays a key role in resistance to the drugs targeting human epidermal growth factor receptor 2 (HER2). Activating mutations in the gene encoding alpha catalytic subunit of PI3K (PIK3CA) are present in approximately 30% of HER2+ tumors. PIK3CA mutations are linked to drug resistance and decreased survival in patients with HER2+ breast cancer. To overcome this resistance mechanism, we designed a phase IB/II clinical trial to evaluate the combination of HER2 small molecule inhibitor tucatinib with PI3K inhibitor alpelisib in patients with HER2+ metastatic breast cancer (NCT05230810). This multicenter clinical trial is conducted through the Academic Breast Cancer Consortium (ABRCC), with the University of Colorado Cancer Center as the lead site. Target enrollment: 40 patients. This is a run-in phase IB/roll-over phase II study. Phase IB will follow Time-to-Event Bayesian Optimal Interval design and enroll from 9 to 19 patients to find the maximum tolerated doses (MTDs) of tucatinib and alpelisib. From 21 to 31 patients will be enrolled in phase II part, for a total of 40 patients in the final efficacy analysis. Main inclusion criteria: 1. Women and men ≥ 18 years old 2. Eastern Cooperative Oncology Group (ECOG) performance status 0-1 3. Presence of activating PIK3CA mutation in the tumor 4. Patients with HR-/HER2+ or HR+/HER2+ breast cancer may enroll; ovarian suppression is mandatory for premenopausal patients with HR+/HER2+ disease 5. HR+/HER2+ patients should be agreeable to concomitant treatment with fulvestrant 6. Prior treatment with at least two FDA-approved HER2-targeted agents 7. Measurable or evaluable disease. Bone only disease is allowed. 8. Subjects with untreated central nervous system (CNS) metastases not needing immediate local therapy, and subjects with previously treated stable or progressive brain metastases may enroll, provided that there is no indication for immediate re-treatment. For patients with treated CNS metastases: time from treatment of CNS disease until the first dose of study drugs should be as follows: WBRT ≥ 21 days, surgical resection ≥ 14 days, SRS ≥ 7 days. 9. Adequate organ and marrow function Main exclusion criteria: 1. Contraindications to undergo contrast brain MRI 2. Leptomeningeal disease 3. Poorly controlled seizures 4. Diabetes mellitus type I, or uncontrolled diabetes mellitus type II 5. Acute pancreatitis within 1 year of screening, or history of chronic pancreatitis 6. History of severe cutaneous hypersensitivity reactions 7. Toxicities of prior cancer therapies that have not resolved to grade 1 or less, except peripheral neuropathy, which must have resolved to grade 2 or less, and alopecia 8. Previous treatment with EGFR or HER2 tyrosine kinase inhibitors, or PI3K/mTOR/AKT inhibitors. 9. Systemic anti-cancer therapy, palliative radiation to extracranial sites, or surgery within 2 weeks of the first dose of study drugs 10. Active bacterial, fungal, or viral infections, hepatitis B, C, or HIV 11. Clinically significant cardio-vascular disease Primary objectives: • Phase IB: safety and tolerability of combination therapy • Phase II: efficacy by progression free survival Exploratory assessment of biomarkers will be performed in the liquid biopsy samples. Study contact: Elena Shagisultanova, MD, PhD, elena.shagisultanova@cuanschutz.edu

Citation Format: Elena Shagisultanova, Kari B. Wisinski, Chelsea D. Gawryletz, Farrah M. Datko, Diana Medgyesy, Jennifer R. Diamond, Virginia F. Borges, Peter Kabos. Clinical Trial of Alpelisib and Tucatinib in Patients with PIK3CA-Mutant HER2-Positive Metastatic Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT3-09-01.

The effects of resistance exercise on appetite sensations, appetite related hormones and energy intake in hormone receptor-positive breast cancer survivors

Appetite is a determinant of dietary intake and is impacted by sex hormones, exercise, and body composition among individuals without chronic conditions. Whether appetite is altered by exercise in the context of estrogen suppression and cancer survivorship is unknown. This randomized cross-over study compared appetite and ad libitum energy intake (EI) after acute resistance exercise (REx) versus sedentary (SED) conditions and in relation to body composition and resting metabolic rate (RMR) in breast cancer survivors (BCS). Physically inactive premenopausal females with previous stage I-III estrogen receptor-positive breast cancer completed a single bout of REx or SED 35 minutes after a standardized breakfast meal. Appetite visual analog scales and hormones (total ghrelin and peptide-YY [PYY]) were measured before and 30, 90, 120, 150, and 180 minutes post-meal and expressed as area under the curve (AUC). Participants were offered a buffet-type meal 180 minutes after breakfast to assess ad libitum EI. Body composition (dual X-ray absorptiometry) and RMR (indirect calorimetry) were measured during a separate visit. Sixteen BCS were included (age: 46 ± 2 y, BMI: 24.9 ± 1.0 kg/m²). There were no differences in appetite ratings or EI between conditions. There were no differences in appetite hormone AUC, but REx resulted in lower ghrelin 120 (-85 ± 39 pg/mL, p = 0.031) and 180 (-114 ± 43 pg/mL, p = 0.018) minutes post-breakfast and higher PYY 90 (21 ± 10 pg/mL, p = 0.028) and 120 (14 ± 7 pg/mL, p = 0.041) minutes post-breakfast. Fat-free mass and RMR negatively correlated with hunger and prospective food consumption AUC after SED, but not REx. In sum, a single REx bout temporarily reduces orexigenic and increases anorexic appetite hormones, but not acute subjective appetite sensations or EI.

Abstract GS4-09: Pregnancy Outcome and Safety of Interrupting Therapy for women with endocrine responsIVE breast cancer: Primary Results from the POSITIVE Trial (IBCSG 48-14/BIG 8-13)

Background: Pregnancy after breast cancer (BC) is of substantial importance for many young women at diagnosis and during follow-up. BC treatment including standard endocrine therapy (ET) (5-10 years) may reduce ovarian reserve and the chances of subsequent successful pregnancy, given conception is contraindicated during ET. A temporary interruption of ET to attempt and carry a pregnancy in this population has never been prospectively studied.

Methods: POSITIVE is a single-arm, prospective, investigator-initiated, international trial evaluating the safety and pregnancy outcomes of interrupting ET for young women with early-stage hormone-receptor-positive (HR+) BC who desire pregnancy. The primary objective is to assess the risk of BC relapse associated with ET interruption for ~2 years to achieve pregnancy. Women ≤42 years with stage I-III HR+ BC who received adjuvant ET (SERM alone, GnRH analogue plus SERM or AI) for 18 to 30 months and wished to interrupt ET to attempt pregnancy were eligible. The primary endpoint is breast cancer free interval (BCFI) defined as the time from enrollment to the first BC event (local, regional, distant recurrence or a new invasive contralateral BC). Planned sample size was 500 patients. Three interim analyses of BCFI were reviewed by the Data Safety Monitoring Committee (DSMC) to assure a 95% chance of stopping the trial early if the annual BCFI event rate exceeded 4%; with primary analysis triggered after 1600 patient years of follow-up (pyfu) and no more than 46 BCFI events defined as the safety threshold. The DSMC recommended continuing the study following each interim analysis. We now report the primary results.

Results: From 12/2014 to 12/2019, 518 women were enrolled. At enrollment, the median age of participants was 37 years (27-43 years); 75.0% were nulliparous, 93.4% had stage I/II disease, 66.3% node-negative. Median time from BC diagnosis to enrollment was 29 months (IQR: 25-32). Tamoxifen alone was the most prescribed ET (41.7%), followed by tamoxifen+ovarian function suppression (35.7%). 62.0% of participants had received neo/adjuvant chemotherapy. At a median follow-up of 41 months (1638 pyfu), 44 participants had experienced a BCFI event, not exceeding the pre-specified safety threshold of 46 events. The 3-year BCFI failure percent was 8.9% (95% CI: 6.3 to 11.6%), similar to the 9.2% (95% CI: 7.6 to 10.8%) calculated in the comparative external control cohort from the SOFT/TEXT trials (Sun et al, Breast 2020). Of 497 women followed for pregnancy status, 368 (74.0%) had at least one pregnancy, 317 (63.8%) had at least one live birth, with a total of 365 babies born. Based on competing risk analysis, 76.3% of patients resumed ET (half within 26 months), 8.3% had BCFI event/death before ET resumption, and 15.4% had not resumed ET yet.

Conclusions: The POSITIVE trial demonstrates that for young women with early HR+ BC desiring pregnancy, temporary interruption of ET to attempt pregnancy does not confer a greater short-term risk of recurrence than that observed in a modern historical control group that did not interrupt ET. Most participants have had a live birth. Further follow-up is planned to confirm long-term safety. These results should be considered in counselling BC patients desiring future pregnancy.

Citation Format: Ann Partridge, Olivia Pagani, Samuel M. Niman, Monica Ruggeri, Fedro Alessandro A. Peccatori, Hatem A. Azim, Marco Colleoni, Cristina Saura, Chikako Shimizu, Anna Saetersdal, Judith Kroep, Audrey Mailliez, Ellen Warner, Virginia F. Borges, Frédéric Amant, Andrea Gombos, Akemi Kataoka, Christine Rousset-Jablonski, Simona Borstnar, Junko Takei, Jeong Eon Lee, Janice Walshe, Manuel Ruiz Borrego, Halle Moore, Christobel Saunders, Vesna Bjelic-Radisic, Snezana Susnjar, Fatima Cardoso, Karen L. Smith, Teresa Ferreiro Vilarino, Karin Ribi, Kathryn Ruddy, Sarra El-Abed, Martine Piccart, Larissa A. Korde, Aron Goldhirsch, Richard D. Gelber. Pregnancy Outcome and Safety of Interrupting Therapy for women with endocrine responsIVE breast cancer: Primary Results from the POSITIVE Trial (IBCSG 48-14/BIG 8-13) [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr GS4-09.

Abstract P5-08-06: Breastfeeding in Survivors of Early Breast Cancer

Background: Breast cancer (BC) is the most common malignancy in women of reproductive age, and the incidence of the disease is rising in this population. Many of these women are interested in childbearing after their BC treatment and a substantial minority will go on to have a live birth. Some will also want to breastfeed. However, there is only limited information available regarding the experience of young BC survivors breastfeeding following treatment. Methods: Participants in the Young Women’s Breast Cancer Study (YWS), a multi-center, prospective cohort study of women diagnosed with BC at age ≤ 40 years between 2006-2016, who reported at least one live birth following their diagnosis with stage 0-III BC were sent an additional survey including investigator-developed questions focused on breastfeeding after breast cancer treatment. Women who had been diagnosed with BC during pregnancy were excluded from this analysis. The survey assessed whether they breastfed, reasons for attempting and stopping breastfeeding, breastfeeding with the treated breast and untreated breast, and supports. Summary statistics, including medians and proportions, are presented. Results: Of 118 eligible women sent a survey, 92 completed the survey (78% response rate). Median age at diagnosis of BC was 32 (range: 17-40) years and at delivery was 37 (range: 29-47) years. 54% of women had attempted to breastfeed (50/92). Among those who had not, 93% noted a history of bilateral mastectomies (39/42). Additional reasons for not attempting to breastfeed included no interest regardless of BC history (5%, 2/42) and 1 woman underwent a unilateral mastectomy and did not think her supply would be sufficient. Among the women who did attempt breastfeeding, 68% had undergone lumpectomy and radiotherapy (34/50) with 85% of those women reporting that the treated breast did not produce milk (29/34). The 5 women who produced milk from the treated breast noted that the supply was substantially less than the untreated breast. To assist with breastfeeding, 76% used a pump only on the untreated breast (38/50) and 14% on both breasts (7/50). Women breastfed for a median of 5.5 (range:&lt; 1-60) months and 64% were “somewhat”/“very much” satisfied with their ability to breastfeed (32/50). The most common reasons cited for stopping breastfeeding included having completed the planned duration (36%, 18/50), to start/resume endocrine therapy (22%, 11/50), and to resume breast imaging (8%, 4/50). Among patients who had not undergone a double mastectomy, 47% recalled receiving specific information about breastfeeding after a history of breast cancer (25/53), most commonly from the oncology team (56%, 14/25), lactation consultant (48%, 12/25), or online resources (44%, 11/25). Conclusion: In the largest series to date detailing the breastfeeding experiences of young BC survivors, approximately half of young BC survivors with a successful pregnancy attempted to breastfeed. Among those who had undergone prior lumpectomy and radiotherapy, women reported no milk production or only limited supply from the treated breast. Despite these limitations, most women who attempted to breastfeed were satisfied with their ability to do so. Specific resources to support the experience of breastfeeding in BC survivors are needed.

Citation Format: Tal Sella, Kimia Sorouri, Shoshana Rosenberg, Margaret Loucks, Kathryn Ruddy, Shari I. Gelber, Rulla M. Tamimi, Jeffrey M. Peppercorn, Lidia Schapira, Virginia F. Borges, Steven E. Come, Ellen Warner, Ann Partridge. Breastfeeding in Survivors of Early Breast Cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-08-06.

Adjuvant endocrine therapy non-initiation and non-persistence in young women with early-stage breast cancer

PURPOSE

Characterizing oral adjuvant endocrine therapy (ET) non-initiation and non-persistence in young women with breast cancer can inform strategies to improve overall adherence in this population.

METHODS

We identified 693 women with hormone receptor-positive, stage I-III breast cancer enrolled in a cohort of women diagnosed with breast cancer at age ≤ 40 years. Women were classified as non-initiators if they did not report taking ET in the 18 months after diagnosis. Women who initiated but did not report taking ET subsequently (through 5-year post-diagnosis) were categorized as non-persistent. We assessed ET decision-making and used logistic regression to identify factors associated with non-initiation/non-persistence and to evaluate the association between non-persistence and recurrence.

RESULTS

By 18 months, 9% had not initiated ET. Black women had higher odds and women with a college degree had lower odds of non-initiation. Among 607 women who initiated, 20% were non-persistent. Younger age, being married/partnered, and reporting more weight problems were associated with higher odds of non-persistence; receipt of chemotherapy and greater hot flash and vaginal symptom burden were associated with lower odds of non-persistence. Adjusting for age and clinical characteristics, non-persistence was associated with lower odds of recurrence. Women who initiated were more likely to report shared decision-making than non-initiators (57% vs. 38%, p = 0.049), while women who were non-persistent were less likely to indicate high confidence with the decision than women who were persistent (40% vs. 63%, p < 0.001).

CONCLUSION

Interventions to improve ET decision-making may facilitate initiation and address barriers to adherence in young breast cancer survivors.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov , NCT01468246.

Abstract PR009: Breast cancer (BC) risk reduction in young women with ductal carcinoma in situ (DCIS)

Background: Young women with DCIS are at increased risk of recurrence and second BC compared to older women and may derive the greatest benefit from risk reduction strategies. Little is known about treatment decision-making, engagement in preventive behaviors, or fear of recurrence among young DCIS survivors. Thus, we sought to investigate treatment and prevention issues in this population. Methods: Using a multicenter prospective cohort that enrolled 1302 women with stage 0-IV BC at age ≤40, we identified participants with DCIS only who completed surveys in the year following diagnosis (dx). Surveys assessed treatment decisions, lifestyle factors (alcohol, smoking, physical activity [PA]), and fear of recurrence (Lasry Scale). Data was summarized with descriptive statistics and groups were compared with Fisher’s exact test. Results: Among 87 patients (median age 38, range 26-40), 75 had available treatment decision data, 19 (25%) of whom had breast-conserving surgery (BCS), 11 (15%) unilateral mastectomy (UM), and 45 (60%) bilateral mastectomy (BM). Most (77%) indicated their doctor said BCS was an option or recommended, including 34 (59%) who had BM. Of 40 patients who reported a patient-driven surgical decision, 73% had BM, 13% UM, and 15% BCS. Among 15 patients who reported the decision as doctor-driven, none had BM, 27% UM, and 73% BCS. Those who had BM were more likely to be extremely confident about the decision (80% vs. 73% UM vs. 53% BCS, p=0.022). Adjuvant tamoxifen was used by 10/27 (37%) patients with ER+ DCIS who had BCS/UM. Most who took tamoxifen reported this decision was shared with their doctor (90%); 1 reported the decision was made on her own. Of the 17 patients who did not take tamoxifen, 88% indicated their doctor said endocrine therapy was an option or recommended. Among all 87 patients, 31 (36%) were former and 3 (4%) were current smokers at baseline assessment (median 5 months post-dx); 51 (59%) never smoked. Overall, 4 quit within 1 year of dx. Most patients (83%) were current drinkers at baseline, though 79% consumed &lt;5 alcoholic beverages/week; 8% reported lower consumption at 1 year. Regarding PA at 1 year, 73% (58/80) reported ≥150 minutes of moderate-intensity PA/week. Overall, 41% of young survivors were at least moderately concerned about their BC coming back, with concern varying numerically by surgery (65% post-BCS, 50% post-UM, 29% post-BM, p=0.053). Conclusions: BC recurrence concerns were frequent among young DCIS patients, particularly among those with remaining breast tissue. BM decisions were largely patient-driven and made with high confidence, reflecting preferences towards surgical prevention. While adherence to survivorship lifestyle guidelines was high, including not smoking, consumption of ≤7 drinks/week, and engaging in PA, tamoxifen use was low, even when offered by a provider. Young DCIS survivors appear motivated to lower future BC risk through surgery and maintenance of healthy behaviors, and less so with tamoxifen; such values should be considered during treatment and survivorship counseling.

Citation Format: Megan E. Tesch, Julia S. Wong, Laura Dominici, Kathryn J. Ruddy, Rulla Tamini, Lidia Schapira, Virginia F. Borges, Ellen Warner, Steven E. Come, Karen Sepucha, Laura C. Collins, Ann H. Partridge, Shoshana M. Rosenberg. Breast cancer (BC) risk reduction in young women with ductal carcinoma in situ (DCIS) [abstract]. In: Proceedings of the AACR Special Conference on Rethinking DCIS: An Opportunity for Prevention?; 2022 Sep 8-11; Philadelphia, PA. Philadelphia (PA): AACR; Can Prev Res 2022;15(12 Suppl_1): Abstract nr PR009.

Clinicopathologic Features, Treatment Patterns, and Disease Outcomes in a Modern, Prospective Cohort of Young Women Diagnosed with Ductal Carcinoma In Situ

BACKGROUND

Ductal carcinoma in situ (DCIS) is uncommon and understudied in young women. The objective of this study is to describe clinicopathologic features, treatment, and oncologic outcomes in a modern cohort of women aged ≤ 40 years with DCIS.

PATIENTS AND METHODS

Patients with DCIS were identified from the Young Women's Breast Cancer Study, a multisite prospective cohort of women diagnosed with stage 0-IV breast cancer at age ≤ 40 years, enrolled from 2006 to 2016. Clinical data were collected from patient surveys and medical records. Pathologic features were examined by central review. Data were summarized with descriptive statistics and groups were compared with χ² and Fisher's exact tests.

RESULTS

Among the 98 patients included, median age of diagnosis was 38 years; 36 (37%) patients were symptomatic on presentation. DCIS nuclear grade was high in 35%, intermediate in 50%, and low in 15% of lesions; 36% of lesions had comedonecrosis. The majority of patients underwent bilateral mastectomy (57%), 16 (16%) underwent unilateral mastectomy, and 26 (27%) underwent lumpectomy, most of whom received radiation. Few (13%) patients were receiving tamoxifen therapy 1 year postdiagnosis. Over a median follow-up of 8.4 years, six patients (6%) had disease recurrence, including five locoregional and one distant event.

CONCLUSIONS

A high proportion of young women with DCIS underwent mastectomy with or without contralateral prophylactic mastectomy. Although DCIS was frequently symptomatic on presentation and exhibited unfavorable pathologic factors, clinicopathologic features were overall heterogeneous and few recurrences occurred. This underscores the need for careful consideration of treatment options in young women with DCIS.

Coping strategies and anxiety in young breast cancer survivors

PURPOSE

We sought to describe coping strategies reported by young breast cancer survivors and evaluate the relationship between utilization of specific coping strategies and anxiety in survivorship.

METHODS

Participants enrolled in The Young Women's Breast Cancer Study, a multi-center, cohort of women diagnosed with breast cancer at age ≤ 40 years, completed surveys that assessed demographics, coping strategies (reported at 6-month post-enrollment and 18-month post-diagnosis), and anxiety (2 years post-diagnosis). We used univariable and multivariable logistic regression to examine the relationship between coping strategies and anxiety.

RESULTS

A total of 833 women with stage 0-3 breast cancer were included in the analysis; median age at diagnosis was 37 (range: 17-40) years. Social supports were the most commonly reported coping strategies, with the majority reporting moderate or greater use of emotional support from a partner (90%), parents (78%), other family (79%), and reliance on friends (88%) at both 6 and 18 months. In multivariable analyses, those with moderate or greater reliance on emotional support from other family (odds ratio (OR): 0.37, 95% confidence ratio (CI): 0.22-0.63) at 18 months were less likely to have anxiety at 2 years, while those with moderate or greater reliance on alcohol/drug use (OR: 1.83, 95%CI: 1.12-3.00) and taking care of others (OR: 1.90, 95%CI: 1.04-3.45) to cope were more likely to have anxiety.

CONCLUSION

Young breast cancer survivors rely heavily on support from family and friends. Our findings underscore the importance of considering patients' social networks when developing interventions targeting coping in survivorship.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01468246 (first posted November 9, 2011).

Replicative Instability Drives Cancer Progression

In the past decade, defective DNA repair has been increasingly linked with cancer progression. Human tumors with markers of defective DNA repair and increased replication stress exhibit genomic instability and poor survival rates across tumor types. Seminal studies have demonstrated that genomic instability develops following inactivation of BRCA1, BRCA2, or BRCA-related genes. However, it is recognized that many tumors exhibit genomic instability but lack BRCA inactivation. We sought to identify a pan-cancer mechanism that underpins genomic instability and cancer progression in BRCA-wildtype tumors. Methods: Using multi-omics data from two independent consortia, we analyzed data from dozens of tumor types to identify patient cohorts characterized by poor outcomes, genomic instability, and wildtype BRCA genes. We developed several novel metrics to identify the genetic underpinnings of genomic instability in tumors with wildtype BRCA. Associated clinical data was mined to analyze patient responses to standard of care therapies and potential differences in metastatic dissemination. Results: Systematic analysis of the DNA repair landscape revealed that defective single-strand break repair, translesion synthesis, and non-homologous end-joining effectors drive genomic instability in tumors with wildtype BRCA and BRCA-related genes. Importantly, we find that loss of these effectors promotes replication stress, therapy resistance, and increased primary carcinoma to brain metastasis. Conclusions: Our results have defined a new pan-cancer class of tumors characterized by replicative instability (RIN). RIN is defined by the accumulation of intra-chromosomal, gene-level gain and loss events at replication stress sensitive (RSS) genome sites. We find that RIN accelerates cancer progression by driving copy number alterations and transcriptional program rewiring that promote tumor evolution. Clinically, we find that RIN drives therapy resistance and distant metastases across multiple tumor types.

Body weight changes and associated predictors in a prospective cohort of young breast cancer survivors

BACKGROUND

Weight gain after a breast cancer diagnosis is common and is associated with inferior outcomes. Young survivors may be especially susceptible to weight changes given the impact of treatment on menopausal status.

METHODS

The authors identified women who were diagnosed with stage 0 to III breast cancer at age 40 years or younger between 2006 and 2016 from a multicenter prospective cohort. Self-reported weight was collected at diagnosis and at 1 year and 3 years postdiagnosis. Tumor and treatment data were obtained from medical records and patient surveys. Multinomial logistic regression was used to identify the factors associated with weight gain (≥5%) or weight loss (≥5%) versus stable weight at 1 year and 3 years postdiagnosis.

RESULTS

The cohort included 956 women with a median age of 37 years at diagnosis. Mean weight significantly increased over time from 66.54 ± 14.85 kg at baseline to 67.33 ± 15.53 and 67.77 ± 14.65 kg at 1 year and 3 years, respectively (p ≤ .001 for both comparisons). The proportion of women experiencing ≥5% weight gain increased from 24.8% at 1 year to 33.9% at 3 years. At 1 year, less self-perceived financial comfort, Black race, and stage III disease were significantly associated with weight gain; at 3 years, only less self-perceived financial comfort remained significant. Baseline overweight or obesity was significantly associated with weight loss at both time points. Chemotherapy, endocrine therapy, and treatment-related menopause were not associated with weight change.

CONCLUSIONS

One third of young breast cancer survivors experienced clinically significant weight gain 3 years after diagnosis; however, treatment-related associations were not observed. Age-appropriate lifestyle interventions, including the reduction of financial barriers, are needed to prevent weight gain in this high-risk population.

Fertility preferences, concerns, and preservation among young women with breast cancer who carry germline genetic pathogenic variants compared with non-carriers

10607

Background: Young women with breast cancer who carry germline genetic pathogenic variants predisposing to breast and other cancers, including BRCA1 or BRCA2, may face unique challenges when making fertility decisions. Limited data exist on differences in fertility preferences, concerns, and preservation strategies between carriers and non-carriers. Methods: Participants in the Young Women’s Breast Cancer Study, a prospective cohort of women diagnosed with breast cancer at ≤ 40 yrs, who completed a baseline survey with a modified Fertility Issues Survey were included in this analysis. Genetic variant status was determined by medical record review complemented by survey self-report. We excluded carriers whose test date was after baseline survey completion or unknown. Fisher exact and Wilcoxon signed-rank tests were used to compare categorical and continuous variables, respectively, between carriers and non-carriers. Results: Of 1052 eligible women, 118 (11%) tested positive for a pathogenic variant (59% BRCA1, 32% BRCA2, 4% TP53, and 5% other unique pathogenic mutations) and 934 (89%) tested negative or were not tested. Carriers’ median age was 36 yrs (range 23-40) vs 37 (range 17-40, p = 0.01) in non-carriers. Similar proportions (p = 0.67) of carriers (38%, [45/118]) and non-carriers (37%, [343/934]) desired more biologic children before diagnosis. Desire declined after diagnosis similarly in both groups (carriers, 25% [29/118] vs non-carriers, 26% [242/934], p = 0.46). Among these women (n = 271), concern about passing on cancer risk to offspring was common and, although numerically higher among carriers, this difference was not statistically significant (carriers, 55% [16/29] vs non-carriers, 40% [96/242], p = 0.12). In contrast, among those not interested in or unsure about future fertility (n = 738), concern about cancer risk heritability was infrequently reported as affecting fertility decisions (carriers, 11% [9/83] vs non-carriers, 9% [56/655], p = 0.54). The same proportions (p = 0.89) of carriers (36% [43/118]) and non-carriers (36% [339/934]) were somewhat or very concerned about becoming infertile after cancer treatment, and fertility preservation strategy utilization was similar between groups (carriers, 11% [13/118] vs non-carriers, 12% [111/934], p = 0.21). Conclusions: Young women with breast cancer who carry germline pathogenic variants are similarly concerned about future fertility and as likely to pursue fertility preservation as non-carriers. Concern about cancer risk heritability was common among both carriers and non-carriers desiring future fertility, suggesting a gap between perceived and actual risk. Genetic counseling should be included in fertility discussions for all young women with breast cancer, with tailored, risk-mitigating recommendations for those who carry genetic variants.

Somatic and Germline Genomic Alterations in Very Young Women with Breast Cancer

PURPOSE

Young age at breast cancer diagnosis correlates with unfavorable clinicopathologic features and worse outcomes compared with older women. Understanding biological differences between breast tumors in young versus older women may lead to better therapeutic approaches for younger patients.

EXPERIMENTAL DESIGN

We identified 100 patients ≤35 years old at nonmetastatic breast cancer diagnosis who participated in the prospective Young Women's Breast Cancer Study cohort. Tumors were assigned a surrogate intrinsic subtype based on receptor status and grade. Whole-exome sequencing of tumor and germline samples was performed. Genomic alterations were compared with older women (≥45 years old) in The Cancer Genome Atlas, according to intrinsic subtype.

RESULTS

Ninety-three tumors from 92 patients were successfully sequenced. Median age was 32.5 years; 52.7% of tumors were hormone receptor-positive/HER2-negative, 28.0% HER2-positive, and 16.1% triple-negative. Comparison of young to older women (median age 61 years) with luminal A tumors (N = 28 young women) revealed three significant differences: PIK3CA alterations were more common in older patients, whereas GATA3 and ARID1A alterations were more common in young patients. No significant genomic differences were found comparing age groups in other intrinsic subtypes. Twenty-two patients (23.9%) in the Young Women's Study cohort carried a pathogenic germline variant, most commonly (13 patients, 14.1%) in BRCA1/2.

CONCLUSIONS

Somatic alterations in three genes (PIK3CA, GATA3, and ARID1A) occur at different frequencies in young versus older women with luminal A breast cancer. Additional investigation of these genes and associated pathways could delineate biological susceptibilities and improve treatment options for young patients with breast cancer. See related commentary by Yehia and Eng, p. 2209.

Overall survival is the lowest among young women with postpartum breast cancer

BACKGROUND

Women diagnosed with breast cancer prior to age 45 years (<45y) and within the first 5 years postpartum (postpartum breast cancer, PPBC) have the greatest risk for distal metastatic recurrence.

METHODS

Pooling data from the Colorado Young Women Breast Cancer cohort and the Breast Cancer Health Disparities Study (N = 2519 cases), we examined the association of parity, age, and clinical factors with overall survival (OS) of breast cancer over 15 years of follow-up.

RESULTS

Women with PPBC diagnosed at <45y had the lowest OS (p < 0.0001), while OS of nulliparous cases diagnosed at <45y did not differ from OS of cases diagnosed at 45-65y regardless of parity status. After adjustment for study site, race/ethnicity, clinical stage, year of diagnosis and stratification for oestrogen receptor status, PPBC remained an independent factor associated with poor OS. Among cases diagnosed at <45y, nulliparous cases had 1.6 times better OS (hazard ratio (HR) = 0.61, 95%CI 0.42-0.87) compared to those with PPBC, with a more pronounced survival difference among stage I breast cancers (HR = 0.30, 95%CI 0.11-0.79). Among very young women diagnosed at age ≤35y, nulliparous cases had 2.3 times better OS (HR = 0.44, 95%CI 0.23-0.84) compared to PPBC.

CONCLUSION

Our results suggest that postpartum status is the main driver of poor prognosis in young women with breast cancer, with the strongest association in patients diagnosed at age ≤35y and in those with stage I disease.

Estradiol (E2) levels in premenopausal women with hormone receptor-positive (HR+) breast cancer (BC) on ovarian function suppression (OFS) with gonadotropin-releasing hormone agonists (GnRHa)

524

Background: OFS is an important treatment component for premenopausal women with early and advanced HR+ BC and optimal efficacy may depend on complete E2 suppression with GnRHa, especially when combined with aromatase inhibitors (AI). However, standard assays lack sensitivity and accuracy at very low E2 concentrations, rendering detection of breakthrough ovarian function challenging. More informative data regarding endocrine effects of GnRHa are needed, particularly in young women who derive the most benefit from OFS yet more frequently had breakthrough E2 levels in the SOFT trial substudy, SOFT-EST. Methods: Using a prospective cohort study of women with BC diagnosed at age ≤ 40 years, we identified participants with stage I-IV HR+ BC on OFS treatment with leuprolide, goserelin or triptorelin and blood collected 1 year after diagnosis. Clinical data were obtained through surveys and medical records. Plasma estrogens were measured by liquid chromatography-tandem mass spectrometry, with a limit of detection of 0.2 pg/mL compared to 10 pg/mL with standard assays. We assessed the proportion of women on OFS with E2 > 2.72 pg/mL (10 pmol/L) and > 10 pg/mL. Patient characteristics, estrone (E1) and FSH levels, and disease-free (DFS) and overall survival (OS) were compared between those with and without elevated E2 using Fischer’s exact, Wilcoxon rank sum and log rank tests, respectively. Results: Of 84 patients who met inclusion criteria, 72 (86%) had stage I-III and 12 (14%) had stage IV BC; 25 were on OFS plus AI and 59 were on OFS plus tamoxifen (TAM). Median E2 was 3.1 pg/mL (range 0.2-30.9). 46 patients (55%) had E2 > 2.72 pg/mL, including 8 on AI and 38 on TAM; 4 (5%) had E2 > 10 pg/mL, including 1 on AI and 3 on TAM. Factors associated with E2 > 2.72 pg/mL were no prior chemotherapy, TAM and high E1 ( P ≤.05), but not age, BMI or GnRHa schedule (Table). After a median follow-up of 7 years, DFS events were seen in 6 patients with E2 > 2.72 pg/mL and 5 without ( P =.232); OS events were seen in 7 patients with E2 > 2.72 pg/mL and 5 without ( P =.608). Conclusions: More than half of young women with ER+ BC had E2 > 2.72 pg/mL on OFS, 91% of whom would not have been detected by standard assays. This may be an area amenable to intervention to improve outcomes in young women. However, larger studies are needed to elucidate the optimal E2 target on OFS and clinical implications of incomplete E2 suppression on ultrasensitive assays. [Table: see text]

NRG-BR002: A phase IIR/III trial of standard of care systemic therapy with or without stereotactic body radiotherapy (SBRT) and/or surgical resection (SR) for newly oligometastatic breast cancer (NCT02364557)

1007

Background: Prospective and retrospective studies of patients (pts) with oligometastatic (OM) disease have supported that metastases (mets) directed treatment (MDT) with SBRT or SR in addition to standard of care systemic therapy (SOC ST) can improve progression-free (PFS) and overall survival (OS) compared with SOC ST alone. However, randomized evidence in oligometastatic breast cancer (OMBC) are lacking. NRG-BR002, a randomized Phase IIR/III trial, sought to determine the efficacy of SOC ST + MDT (SBRT or SR) as first line treatment of OMBC. Methods: OMBC pts with ≤ 4 extracranial mets on standard imaging with controlled primary disease were eligible if on first line SOC ST for ≤ 12 months without progression. Pts were randomized (1:1) to ARM 1 – SOC ST (mainly chemotherapy, endocrine therapy, anti-HER2) or ARM 2 – SOC ST with MDT of all mets. Stratification included mets number (1 vs > 1), ER/PR and Her2 status, and chemotherapy use. Phase IIR targeted sample size was 128 total/116 eligible pts, for 92% power and 1-sided significance level = 0.15 to determine if adding MDT shows a signal for improved PFS (hazard ratio [HR] = 0.55, corresponding to median PFS (mPFS) from 10.5 to 19 months), in order to continue to the full phase III trial for OS. PFS and OS were estimated by Kaplan-Meier and arms compared with log-rank. Results: 125 of the 129 pts randomized were eligible (ARM 1 = 65, ARM 2 = 60). Key characteristics included median age 54, 79% ER+ or PR+/HER2-, 13% HER2+, 8% triple negative. 60% had 1 metastasis and 20% presented synchronously with primary disease. Following randomization, systemic therapy was delivered to 95% in ARM 1 and 93% in ARM 2; ablation: SBRT 93%, SR 2%, and 5% none. The median follow-up was 30 mo. The mPFS (70% CI) in ARM 1 was 23 mo (18, 29) and 19.5 mo (17, 36) in ARM 2; 24 and 36-mo PFS (70% CI) for ARM 1 were 45.7% (38.9, 52.5) and 32.8% (26.0, 39.5) compared with 46.8 (39.2, 54.3) and 38.1 (29.7, 46.6) in ARM 2; HR (70% CI): 0.92 (0.71, 1.17); and 1-sided log-rank p = 0.36. As PFS did not show signal, OS reporting is included: median OS was not reached in either arm; 36-mo OS (95% CI) in ARM 1 71.8% (58.9, 84.7) and ARM 2 68.9% (55.1, 82.6; 2-sided log-rank p = 0.54). Analysis of first failure showed new mets outside index area (Arm 1) /RT field (Arm 2) developed similarly in both arms at 40%. There were fewer new mets inside treated/index area for Arm 2 6.7% vs ARM 1 29.2%, respectively. There were no grade 5 treatment-related adverse events (AEs), 1 grade 4 AE in ARM 1, and 9.7% and 5.3% grade 3 AEs in ARMS 1 and 2, respectively. Circulating tumor cell counts (0 vs ≥1) at baseline were similar in both arms and were not prognostic HR (95% CI): 1.04 (0.54, 2.02). Conclusions: The addition of MDT to SOC ST did not show signal for improved PFS, nor OS difference in patients with OMBC. The trial will not proceed to the Phase III component. Clinical trial information: NCT02364557.

PIK3CA Mutations Drive Therapeutic Resistance in Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

The phosphatidylinositol 3-kinase (PI3K) pathway is an intracellular pathway activated in response to progrowth signaling, such as human epidermal growth factor receptor 2 (HER2) and other kinases. Abnormal activation of PI3K has long been recognized as one of the main oncogenic drivers in breast cancer, including HER2-positive (HER2+) subtype. Somatic activating mutations in the gene encoding PI3K alpha catalytic subunit (PIK3CA) are present in approximately 30% of early-stage HER2+ tumors and drive therapeutic resistance to multiple HER2-targeted agents. Here, we review currently available agents targeting PI3K, discuss their potential role in HER2+ breast cancer, and provide an overview of ongoing trials of PI3K inhibitors in HER2+ disease. Additionally, we review the landscape of PIK3CA mutational testing and highlight the gaps in knowledge that could present potential barriers in the effective application of PI3K inhibitors for treatment of HER2+ breast cancer.

Trajectories of fear of cancer recurrence in young breast cancer survivors

BACKGROUND

Fear of cancer recurrence (FCR) is more intense in younger women. Because FCR is a powerful determinant of quality of life, identifying those at risk for persistently elevated FCR can inform timing of interventions.

METHODS

A total of 965 women with stage 0 to stage III breast cancer enrolled in the Young Women's Breast Cancer Study, a prospective cohort of women diagnosed with breast cancer at age ≤40 years, completed the 3-item Lasry Fear of Recurrence Index. Group-based trajectory modeling was used to classify distinct FCR patterns from baseline through 5 years post-diagnosis. Multinomial logistic regression was used to identify patient, disease, and treatment characteristics associated with each trajectory.

RESULTS

Five FCR trajectories were identified with the majority of participants having moderate (33.1%) or high FCR (27.6%) that improved over time. A total of 6.9% participants had moderate FCR that worsened, whereas 21.7% had high FCR at baseline that remained high throughout. In the fully adjusted multinomial model, stages II and III (vs stage I) were associated with lower odds (of being in the high/stable trajectory). White (vs non-White) were associated with higher odds of being in a trajectory that improved over time.

CONCLUSIONS

Although FCR improves over time for many young women with breast cancer, approximately one-third had FCR that was severe and did not improve or worsened over 5 years after diagnosis. Ongoing monitoring is warranted, with early referral to mental health professionals indicated for those at highest risk for unresolved FCR.

LAY SUMMARY

Fear of recurrence is common among young women with breast cancer. The authors followed a large cohort of young women diagnosed with breast cancer when they were 40 years of age and younger, and found 5 distinct trajectories that show moderate and severe fears do not always improve over time and may require targeted mental health intervention.

Triple Targeting of Breast Tumors Driven by Hormonal Receptors and HER2

Breast cancers that express hormonal receptors (HR) and HER2 display resistance to targeted therapy. Tumor-promotional signaling from the HER2 and estrogen receptor (ER) pathways converges at the cyclin D1 and cyclin-dependent kinases (CDK) 4 and 6 complex, which drives cell-cycle progression and development of therapeutic resistance. Therefore, we hypothesized that co-targeting of ER, HER2, and CDK4/6 may result in improved tumoricidal activity and suppress drug-resistant subclones that arise on therapy. We tested the activity of the triple targeted combination therapy with tucatinib (HER2 small-molecule inhibitor), palbociclib (CKD4/6 inhibitor), and fulvestrant (selective ER degrader) in HR⁺/HER2⁺ human breast tumor cell lines and xenograft models. In addition, we evaluated whether triple targeted combination prevents growth of tucatinib or palbociclib-resistant subclones in vitro and in vivo Triple targeted combination significantly reduced HR⁺/HER2⁺ tumor cell viability, clonogenic survival, and in vivo growth. Moreover, survival of HR⁺/HER2⁺ cells that were resistant to the third drug in the regimen was reduced by the other two drugs in combination. We propose that a targeted triple combination approach will be clinically effective in the treatment of otherwise drug-resistant tumors, inducing robust responses in patients.

Options for Endocrine-Refractory, Hormone Receptor-Positive Breast Cancer: Which Target and When?

The Oncology Grand Rounds series is designed to place original reports published in the Journal into clinical context. A case presentation is followed by a description of diagnostic and management challenges, a review of the relevant literature, and a summary of the authors' suggested management approaches. The goal of this series is to help readers better understand how to apply the results of key studies, including those published in Journal of Clinical Oncology, to patients seen in their own clinical practice.

Alliance A011801 (compassHER2 RD): postneoadjuvant T-DM1 + tucatinib/placebo in patients with residual HER2-positive invasive breast cancer

This report describes the rationale, purpose and design of A011801 (CompassHER2 RD), an ongoing prospective, multicenter, Phase III randomized trial. Eligible patients in the United States (US) and Canada with high-risk (defined as ER-negative and/or node-positive) HER2-positive (HER2+) residual disease (RD) after a predefined course of neoadjuvant chemotherapy and HER2-directed treatment are randomized 1:1 to adjuvant T-DM1 and placebo, versus T-DM1 and tucatinib. Patients have also received adjuvant radiotherapy and/or endocrine therapy, if indicated per standard of care guidelines. The primary objective of the trial is to determine if the invasive disease-free survival (iDFS) with T-DM1 plus tucatinib is superior to iDFS with T-DM1 plus placebo; other outcomes of interest include overall survival (OS), breast cancer-free survival (BCFS), distant recurrence-free survival (DRFS), brain metastases-free survival (BMFS) and disease-free survival (DFS). Correlative biomarker, quality of life (QoL) and pharmacokinetic (PK) end points are also evaluated.

Association of Local Therapy With Quality-of-Life Outcomes in Young Women With Breast Cancer

Importance

Increasing rates of bilateral mastectomy have been most pronounced in young women with breast cancer, but the association of surgery with long-term quality of life (QOL) remains largely unknown.

Objective

To examine the association of surgery with longer-term satisfaction and QOL in young breast cancer survivors.

Design, Setting, and Participants

This multicenter cross-sectional study of a prospective cohort was conducted from October 2016 to November 2017, at academic and community hospitals in North America. Women 40 years or younger enrolled in the Young Women's Breast Cancer Study were assessed. Data analysis was performed from during a 1- to 2-year period after conclusion of the study.

Exposures

Primary breast surgery, reconstruction, and radiotherapy.

Main Outcomes and Measures

Mean BREAST-Q breast satisfaction and physical, psychosocial, and sexual well-being scores were compared by type of surgery; higher BREAST-Q scores (range, 0-100) indicate better QOL. Linear regression was used to identify demographic and clinical factors associated with BREAST-Q scores for each domain.

Results

A total of 560 women with stage 0 to III breast cancer (median age at diagnosis, 36 years; range, 17-40 years; 484 [86%] with stage 0-II disease) completed the BREAST-Q a median of 5.8 years (range, 1.9-10.4 years) from diagnosis. A total of 290 patients (52%) of patients underwent bilateral mastectomy, 110 patients (20%) underwent unilateral mastectomy, and 160 patients (28%) received breast-conserving therapy. Among mastectomy patients, 357 (89%) had reconstruction and 181 (45%) received radiotherapy. In multivariate analyses, implant-based reconstruction (vs autologous) was associated with decreased breast satisfaction (β = -7.4; 95% CI, -12.8 to -2.1; P = .007) and complex reconstruction (vs autologous) with worse physical well-being (β = -14.0; 95% CI, -22.2 to -5.7; P < .001).

Conclusions and Relevance

These results suggest that local therapy in young breast cancer survivors is persistently associated with poorer scores in multiple QOL domains, particularly among those treated with mastectomy and radiotherapy, irrespective of breast reconstruction. Socioeconomic stressors also appear to play a role.

Who are the women who enrolled in the POSITIVE trial: A global study to support young hormone receptor positive breast cancer survivors desiring pregnancy

Background

Premenopausal women with early hormone-receptor positive (HR+) breast cancer receive 5–10 years of adjuvant endocrine therapy (ET) during which pregnancy is contraindicated and fertility may wane. The POSITIVE study investigates the impact of temporary ET interruption to allow pregnancy.

Methods

POSITIVE enrolled women with stage I-III HR + early breast cancer, ≤42 years, who had received 18–30 months of adjuvant ET and wished to interrupt ET for pregnancy. Treatment interruption for up to 2 years was permitted to allow pregnancy, delivery and breastfeeding, followed by ET resumption to complete the planned duration.

Findings

From 12/2014 to 12/2019, 518 women were enrolled at 116 institutions/20 countries/4 continents. At enrolment, the median age was 37 years and 74.9 % were nulliparous. Fertility preservation was used by 51.5 % of women. 93.2 % of patients had stage I/II disease, 66.0 % were node-negative, 54.7 % had breast conserving surgery, 61.9 % had received neo/adjuvant chemotherapy. Tamoxifen alone was the most prescribed ET (41.8 %), followed by tamoxifen + ovarian function suppression (OFS) (35.4 %). A greater proportion of North American women were <35 years at enrolment (42.7 %), had mastectomy (59.0 %) and received tamoxifen alone (59.8 %). More Asian women were nulliparous (81.0 %), had node-negative disease (76.2%) and received tamoxifen + OFS (56.0 %). More European women had received chemotherapy (69.3 %).

Interpretation

The characteristics of participants in the POSITIVE study provide insights to which patients and doctors considered it acceptable to interrupt ET to pursue pregnancy. Similarities and variations from a regional, sociodemographic, disease and treatment standpoint suggest specific sociocultural attitudes across the world.

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Fertility and pregnancy are priority concerns for young breast cancer survivors.

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POSITIVE explores a transient interruption of endocrine therapy to allow conception.

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Patients' characteristics highlight features considered suitable to study enrolment.

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Overall, patients enrolled had a relatively high median age and low-risk disease.

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Variations emerged across continents suggesting specific sociocultural attitudes.

Treatment-related amenorrhea in a modern, prospective cohort study of young women with breast cancer

Young women with breast cancer experience unique treatment and survivorship issues centering on treatment-related amenorrhea (TRA), including fertility preservation and management of ovarian function as endocrine therapy. The Young Women's Breast Cancer Study (YWS) is a multi-center, prospective cohort study of women diagnosed at age ≤40, enrolled from 2006 to 2016. Menstrual outcomes were self-reported on serial surveys. We evaluated factors associated with TRA using logistic regression. One year post-diagnosis, 286/789 (36.2%) experienced TRA, yet most resumed menses (2-year TRA: 120/699; 17.2%). Features associated with 1-year TRA included older age (OR≤30vs36-40 = 0.29 (0.17-0.48), OR31-35vs36-40 = 0.67 (0.46-0.94), p = 0.02); normal body mass index (BMI) (OR≥25vs18.5-24. =0.59 (0.41-0.83), p < 0.01); chemotherapy (ORchemo vs no chemo = 5.55 (3.60-8.82), p < 0.01); and tamoxifen (OR = 1.55 (1.11-2.16), p = 0.01). TRA rates were similar across most standard regimens (docetaxel/carboplatin/trastuzumab +/- pertuzumab: 55.6%; docetaxel/cyclophosphamide +/- trastuzumab/pertuzumab: 41.8%; doxorubicin/cyclophosphamide/paclitaxel +/- trastuzumab/pertuzumab: 44.1%; but numerically lower with AC alone (25%) or paclitaxel/trastuzumab (11.1%). Among young women with breast cancer, lower BMI appears to be an independent predictor of TRA. This finding has important implications for interpretation of prior studies, future research, and patient care in our increasingly obese population. Additionally, these data describe TRA associated with use of docetaxel/cyclophosphamide, which is increasingly being used in lieu of anthracycline-containing regimens. Collectively, these data can be used to inform use of fertility preservation strategies for women who need to undergo treatment as well as the potential need for ovarian suppression following modern chemotherapy for young women with estrogen-receptor-positive breast cancer.Clinical trial registration: www.clinicaltrials.gov, NCT01468246.

Vitamin D as a Potential Preventive Agent For Young Women's Breast Cancer

Clinical studies backed by research in animal models suggest that vitamin D may protect against the development of breast cancer, implicating vitamin D as a promising candidate for breast cancer prevention. However, despite clear preclinical evidence showing protective roles for vitamin D, broadly targeted clinical trials of vitamin D supplementation have yielded conflicting findings, highlighting the complexity of translating preclinical data to efficacy in humans. While vitamin D supplementation targeted to high-risk populations is a strategy anticipated to increase prevention efficacy, a complimentary approach is to target transient, developmental windows of elevated breast cancer risk. Postpartum mammary gland involution represents a developmental window of increased breast cancer promotion that may be poised for vitamin D supplementation. Targeting the window of involution with short-term vitamin D intervention may offer a simple, cost-effective approach for the prevention of breast cancers that develop postpartum. In this review, we highlight epidemiologic and preclinical studies linking vitamin D deficiency with breast cancer development. We discuss the underlying mechanisms through which vitamin D deficiency contributes to cancer development, with an emphasis on the anti-inflammatory activity of vitamin D. We also discuss current evidence for vitamin D as an immunotherapeutic agent and the potential for vitamin D as a preventative strategy for young woman's breast cancer.

Abstract 790: A Utah Population Data Base Study of young women's breast cancer outcomes by parity status

Importance: A diagnosis of breast cancer after childbirth is reported to increase risk for metastasis and death in patients ≤45 years of age. Data to discern if a postpartum diagnosis is an independent risk factor for poor outcomes remain limited.

Objective: Determine associations between time since last pregnancy and time to metastasis and breast cancer-specific death using cases available from the Utah Population Data Base (UPDB). Secondary objectives are time to metastasis and breast cancer specific-death delineated by tumor stage and ER status. Study Design: This is a population-based study of 2,977 women with stage I, II, or III breast cancer (BC) diagnosed at ≤ 45 years of age from 1996 to 2017. The study population was identified from the UPDB, a statewide dynamic database of linked data received from the Utah SEER Cancer Registry, birth certificates, death certificates, and medical records. Clinical prognostic factors include patient age at diagnosis, year of diagnosis, tumor size, stage, and estrogen receptor (ER) status. The primary exposures are no prior childbirth or time between the most recent childbirth and a breast cancer diagnosis, and primary outcomes are distant metastasis-free survival and breast cancer specific death.

Results: Among the 2,977 predominantly white women from the state of Utah, USA, the reproductive histories of the breast cancer patients were grouped as nulliparous (n = 867), and parous: diagnosed 0-5 years (n = 614), &gt;5-10 years (n = 615) and &gt;10 years (n = 881) since last childbirth. We find a breast cancer diagnosis within 5 years of childbirth is associated with elevated risk for metastasis after controlling for diagnosis year, diagnosis age, tumor stage, and ER status [HR (95% CI) =1.64 (1.16, 2.32)], particularly in Stage I/II disease [HR (95% CI) =1.89 (1.24, 2.87)]. The 0-5 year group also had elevated risk of breast cancer-specific death [HR (95% CI) =1.57 (1.07, 2.32)]. While ER-negative tumors were enriched in women diagnosed 0-5 years postpartum, this enrichment could be attributed largely to the younger age of this reproductive group. Further, postpartum breast cancer patients diagnosed with ER-positive disease within 5 years of a completed pregnancy had significantly worse distant metastasis-free survival than nulliparous patients with ER-negative disease.

Conclusions: In this population level study from the state of Utah, a diagnosis of breast cancer within 5 years postpartum is a risk factor for metastasis and breast cancer-specific death that is independent of known clinical parameters, including ER status. The increased risk for poor outcomes is highest in stage I/II diagnoses. Relevance: For women with breast cancers classically considered as having good prognostic tumor features, i.e. stage I or II and ER-positive, a postpartum diagnosis is a dominant demographic feature of increased risk for metastasis and death.

Citation Format: Pepper Schedin, Sonali Jindal, Solange Bassale, Zhenzhen Zhang, Alison Fraser, Emily Guinto, Virginia F. Borges, Motomi Mori, Ken R. Smith. A Utah Population Data Base Study of young women's breast cancer outcomes by parity status [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 790.

Updated results of tucatinib versus placebo added to trastuzumab and capecitabine for patients with pretreated HER2+ metastatic breast cancer with and without brain metastases (HER2CLIMB)

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Background: Tucatinib (TUC) is an oral tyrosine kinase inhibitor (TKI) highly specific for HER2. TUC is approved for use in combination with trastuzumab (T) and capecitabine (C) in patients (pts) with and without brain metastases (BM) who have received 1 or more prior anti-HER2–based regimens in the metastatic setting. In the primary analysis from the pivotal HER2CLIMB trial, the addition of TUC to T and C in pts with HER2+ metastatic breast cancer showed a statistically significant and clinically meaningful prolongation of progression-free (PFS) (HR = 0.54 [95% CI: 0.42, 0.71]; P < 0.001) and overall survival (OS) (HR = 0.66 [95% CI: 0.50, 0.88]; P = 0.005) (Murthy, et al. NEJM 2020). TUC in combination with T and C was well tolerated with few discontinuations other than for disease progression. Based on these data, the protocol was amended for unblinding of sites to treatment assignment to allow for crossover from the placebo arm to receive TUC in combination with T and C. Methods: HER2CLIMB (NCT02614794) is a global, randomized, double-blind, placebo-controlled trial in pts with unresectable locally advanced or metastatic HER2+ breast cancer previously treated with T, pertuzumab, and T-emtansine (T-DM1), including pts with untreated, treated stable, or treated and progressing BM. Overall 612 pts were randomized 2:1 to receive TUC 300 mg BID or placebo, each in combination with T and C. Randomization was stratified by BM, ECOG performance status, and geographic region. Protocol prespecified analysis of OS, PFS (by investigator assessment) and safety in the total study population will be performed at approximately 2 years from the last patient randomized. Results: Updated Kaplan-Meier time-to-event analysis of OS and PFS with hazard ratios and 95% confidence intervals for TUC arm vs placebo arm will be presented overall, as well as for OS in the prespecified subgroups reported previously (Murthy, et al. NEJM 2020). Safety and tolerability assessments will include frequency of adverse events by severity, dose modifications and discontinuation of study medications. Conclusions: Conclusions will be presented in the presentation. Clinical trial information: NCT02614794 .

A011801 (CompassHER2 RD): Postneoadjuvant T-DM1 + tucatinib/placebo in patients with residual HER2-positive invasive breast cancer

TPS595

Background: Patients (pts) with HER2+ early breast cancer (EBC) and invasive residual disease (RD) after neoadjuvant therapy (NAT) have a higher risk of relapse than pts with a pathologic complete response (pCR). Post neoadjuvant T-DM1 has improved invasive disease-free survival (iDFS), but pts with estrogen receptor (ER)-negative or nodal RD have suboptimal outcomes and recurrences in the central nervous system are a problem. More effective treatment strategies are needed. The CompassHER2 trials, EA1181 and A011801, leverage pCR to tailor post neoadjuvant therapy in HER2+ EBC. EA1181 is a NAT de-escalation trial of a taxane, trastuzumab and pertuzumab (THP) in clinical stage II-III HER2+ EBC; pts with a pCR complete HP +/- adjuvant radiation (RT) +/- endocrine therapy (ET). A011801 is an escalation trial for pts with high risk HER2+ RD after NAT, examining addition of the HER2 selective tyrosine kinase inhibitor (TKI) tucatinib to adjuvant T-DM1. Methods: Eligibility and Intervention: Pts. with high-risk HER2+ RD (e.g. ER-,node-positive, or both) after a predefined course of neoadjuvant HER2-directed treatment are randomized 1:1 to adjuvant T-DM1+ placebo (pb), vs. T-DM1 and tucatinib with adjuvant RT +/- ET. Eligibility criteria include completion of ≥ 6 cycles of NAT, including ≥ 9 weeks of T and H +/- P. All chemotherapy (CT) must be completed preoperatively unless participating in EA1181 (̃15-30% enrollees); these pts must receive postoperative CT to complete ≥ 6 cycles prior to enrollment on A011801. Pts who received prior HER2-targeted TKIs or antibody-drug conjugates are ineligible. Objectives: The primary objective is to determine if iDFS is higher with addition of T-DM1 to tucatinib in pts with HER2+ EBC with RD after NAT; secondary endpoints include overall survival, breast cancer free survival, distant recurrence-free survival, brain metastases-free survival and disease-free survival. Correlative objectives include the association of i) tumor infiltrating lymphocyte (TILs) levels in the primary tumor and RD with iDFS, ii) TILs with tucatinib benefit, iii) iDFS and circulating tumor cells (CTC) at serial timepoints and iv) the magnitude of benefit of tucatinib (iDFS) in pts with/without detectable pretreatment CTCs. Quality of life and pharmacokinetic endpoints will also be evaluated. Statistics: A011801 is a prospective, double-blind, randomized, phase III superiority trial; stratified by i) receipt of postoperative CT (Y/N), ii) hormone receptor-status (+/-),and iii) pathologic lymph node status (+/-). The study targets an absolute difference of 5% in iDFS (control vs. experimental arm 82% & 87%, HR = 0.7), with a two-sided alpha of 0.05 and power of 80%. The sample size is 981; target accrual = 1031 pts; activation and completion dates are 01/6/21 and ̃ 01/2028. Support: U10CA180821, U10CA180882; Seagen Inc; ClinicalTrials.gov Identifier: NCT04457596 Clinical trial information: NCT04457596.

Association of cancer treatment with excess heart age among young breast cancer survivors

12081

Background: Young women with breast cancer may be at increased risk for premature development of cardiovascular disease (CVD) in part due to their cancer treatment. Limited data are available on CVD risk among young breast cancer survivors. Methods: Women aged 30-40 years at diagnosis with stage 0-III breast cancer enrolled in a prospective cohort study of women diagnosed with breast cancer at ≤40 were eligible for inclusion in this analysis. Data were obtained from serial surveys and electronic medical records at breast cancer diagnosis and 5-year follow-up. We calculated “excess heart age,” which incorporates a CVD risk-based score (calculated using age, systolic blood pressure, blood pressure medication, diabetes, smoking, body mass index) to estimate the difference in years between an individual’s chronological age and their CVD-risk adjusted age. Multivariable logistic regression models (adjusting for age at diagnosis, stage, and race) were fitted to evaluate associations between treatment (radiation, endocrine therapy, anthracyclines, and trastuzumab) and having a change in excess heart age ≥2 years from baseline to 5 years. Results: Among 372 young breast cancer survivors, mean age at diagnosis was 36.6 (SD 2.89), 93% were white, and 79% were diagnosed with stage I or II breast cancer. Mean excess heart age was.32 (SD: 6.16) years at baseline, which declined to -.07 (SD 6.64) at 5-year follow-up (p=.17). At 5 years, 31% (n=114) of women experienced an increase of at least 2 years in their excess heart age since diagnosis, and their mean excess heart age was 4.34 years (range -9 to 30). In multivariable analyses, receipt of trastuzumab was associated with higher odds (OR: 1.68, 95% CI: 1.02-2.77) of experiencing an increase of ≥2 years in excess heart age between diagnosis and 5 years of follow-up. Endocrine therapy, anthracyclines, and radiation were not significantly associated with a change in excess heart age of ≥2 years at 5 years post-diagnosis. Conclusions: At 5 years post-diagnosis, approximately 1/3 of young breast cancer survivors experienced a change from baseline in their excess heart age of ≥2 years. Further research is warranted to confirm findings regarding trastuzumab and excess heart age, and potential effects on longer-term cardiac outcomes in this population. Extended follow-up of this cohort may further quantify CVD risk over time.[Table: see text]

Twenty-one-gene recurrence score (RS) in germline (g)CHEK2 mutation-associated versus sporadic breast cancers (BC): A multi-site case-control study

10531

Background: Genomic assays, such as RS, are used to determine chemotherapy benefit in early-stage, estrogen receptor (ER)- and/or progesterone receptor (PR)-positive, HER2 negative BC patients (pts). Currently, guidelines to use pts’ germline genetic testing results to guide adjuvant therapy are lacking. Several reports have indicated worse outcomes for BC pts with g CHEK2 pathogenic variants (PV). We investigated whether PV in CHEK2 were associated with increased RS. Methods: Patient-level clinical data and RS were derived from electronic medical records of seven medical centers between years 2013-17. Confirmation of RS using the Genomic Health provider portal was performed. 38 pts with germline PV in CHEK2 (15 pts/39.5% with c.1100delC mutation) and RS score (cases) were matched with BC pts whose genetic testing did not identify PV (controls) using a 1:2 matching schema. Pts were matched based on age at diagnosis and lymph node (LN) status. LN negative pts were further matched based on T-stage. A multivariate random intercept linear mixed model of CHEK2 mutation status on RS was performed, adjusting for PR. A secondary ordinal univariate analysis was conducted that categorized RS into low, intermediate and high risk ( < 18, 18-30, and > 30, respectively). P-values were reported based on a null hypothesis of no effect against a two-sided alternative. Results: The median RS for cases was 19.5 (interquartile range [IQR]: 15 to 25) and the median RS for controls was 18 (IQR: 12 to 22). A greater proportion of cases were categorized as high risk (10.5%) compared to controls (5.6%), and a smaller proportion of cases were categorized as low risk (36.8%) compared to controls (49.3%). Cases had higher grade and increased proportion of PR-negative BC as compared with controls (grade 1: 12.1% of cases versus 32.4% of controls; PR-negative: 7.9% of cases versus 5.6% of controls). The variables used to match cases and controls (age, lymph node status, and T-stage) had similar summary statistics. The RS was 1.97-point higher in pts with g CHEK2 PV compared to controls, after adjusting for PR (95% confidence interval [CI]: 1.02-point lower to 4.96-point higher; p = 0.194). The secondary analysis of CHEK2 mutation status on an ordinal RS risk group yielded comparable results; on average, the odds of being high risk compared to the combined intermediate/low risk groups was 1.72 times higher in cases compared to controls (95% CI: 0.77 to 3.80; p = 0.181), but these differences were not significant. Conclusions: Our case-control study did not show a statistically higher RS for BC that develops in pts with g CHEK2 PV. Further studies are warranted to evaluate the association between type of CHEK2 PV (frameshift versus missense) and other modifying genetic variables and RS.

Testing for clonal hematopoiesis of indeterminate potential in breast cancer survivors

e24108

Background: Clonal hematopoiesis of Indeterminate Potential (CHIP) is associated with adverse clinical outcomes including increased risk of hematologic malignancies and heart disease. Limited data suggest an increased prevalence of CHIP in patients treated for solid tumors, particularly after exposure to radiation and chemotherapy. CHIP testing may inform risk-reduction strategies for cancer survivors. Little is known about patient knowledge, attitudes, and preferences regarding CHIP testing. Methods: We surveyed survivors without history of recurrence participating in an ongoing prospective cohort study of young women with breast cancer (BC). The survey was sent by email and included an introduction to CHIP including risk factors and clinical associations. Respondents then reviewed a vignette and were asked about CHIP testing preferences (definitely/probably test vs. definitely/probably not test) considering sequentially: 1) population-based 10-year risk of BC recurrence, hematological malignancy and heart disease; 2) estimated increase in these risks with CHIP; 3) current CHIP management; 4) a dedicated CHIP clinic; and 5) a theoretical CHIP treatment. Changes in preferences from the prior scenario were evaluated with the McNemar's test using a type I error rate of 5%. Results: 528/642 (82.2%) eligible women responded to the survey, at a median age of 46 (range: 31-54) years (median time from diagnosis: 108 months (range: 60-168)), and 88% were white. Most had stage 1/2 BC (78.8%) and had received chemotherapy (73.1%) and/or radiation (61.9%). 93.6% had never heard of CHIP prior to survey. After initial patient vignette presentation, most women (87.1%,) recommended CHIP testing if offered. Preferences for testing decreased (p<0.05) when considering population-based risks, with 11.1% shifting their preference from CHIP testing to not testing. After considering increased risks associated with CHIP, interest in testing increased (p<0.05), with 10.1% shifting their preference to testing. Interest significantly (p<0.05) increased with the possibility of managing CHIP through a clinic or a hypothetical CHIP treatment, with 7.2% and 14.1% switching their preferences towards testing, respectively. Finally, 75.8% responded that they themselves, after learning about CHIP and reviewing the vignette, would want to have CHIP testing; 28.2% reported that learning about CHIP and the associated risks caused them at least moderate anxiety. Conclusion: Few young BC survivors were aware of CHIP yet most indicated an interest in testing after learning about it. Testing preferences were influenced by risks presented and potential management strategies. Findings highlight the importance of effective risk communication and the need for adequate psychosocial support when considering testing for CHIP and other potential clinical biomarkers predictive of cancer and other medical risks in cancer survivors.

Impact of fertility concerns on endocrine therapy decisions in young breast cancer survivors

BACKGROUND

The diagnosis and treatment of breast cancer can have profound effects on a young woman's family planning and fertility, particularly among women with hormone receptor-positive breast cancer.

METHODS

The Young Women's Breast Cancer Study was a multicenter cohort of women aged 40 years or younger and newly diagnosed with breast cancer from 2006 to 2016. Surveys included assessments of fertility concerns, endocrine therapy (ET) preferences, and use. Characteristics were compared between women who reported that fertility concerns affected ET decisions and those who did not. Logistic regression was used to identify factors associated with having an ET decision affected by fertility concerns.

RESULTS

Of 643 eligible women with hormone receptor-positive, stage I to III breast cancer, one-third (213 of 643) indicated that fertility concerns affected ET decisions. In a multivariable analysis, only parity at diagnosis was significantly associated with fertility concerns affecting ET decisions (odds ratio for nulliparous vs ≥2 children, 6.96; 95% confidence interval, 4.09-11.83; odds ratio for 1 vs ≥2 children, 5.30; 95% confidence interval, 3.03-9.87). Noninitiation/nonpersistence was higher among women with fertility concerns versus those without fertility concerns (40% vs 20%; P < .0001). Among women with fertility-related ET concerns, 7% (15 of 213) did not initiate ET, and 33% (70 of 213) were nonpersistent over 5 years of follow-up. Of these women, 66% (56 of 85) reported 1 or more pregnancies or pregnancy attempts; 27% (15 of 56) had resumed ET at the last available follow-up through 5 years.

CONCLUSIONS

Concern about fertility is a contributor to adjuvant ET decisions among a substantial proportion of young breast cancer survivors. Ensuring family planning is addressed in the setting of ET recommendations should be a priority throughout the cancer care continuum.

Arm Morbidity After Local Therapy for Young Breast Cancer Patients

BACKGROUND

The impact of patient demographics and local therapy choice on arm morbidity in young breast cancer patients is understudied despite its importance given the long survivorship period. This study assessed patient-reported arm morbidity in the Young Women's Breast Cancer Study (YWS), a prospective cohort study.

METHODS

From 2006 to 2016, 1302 women with breast cancer diagnosed at the age of 40 years or younger enrolled in the YWS. The participants regularly complete surveys. The response rates are higher than 86%. Using the Breast Cancer Prevention Trial Checklist, this study examined the prevalence of patient-reported postoperative arm swelling and decreased range of motion (ROM) 1 year after diagnosis, stratified by local therapy strategy, in patients who had surgery for stages 1 to 3 disease. Logistic regression analysis was used to identify risk factors for arm morbidity.

RESULTS

Among 888 eligible participants (median age, 37 years), 14% reported arm swelling and 34% reported decreased ROM at 1 year. Arm swelling was reported by 23.6% of the patients who had axillary lymph node dissection (ALND) and 24.6% of the patients who received ALND and post-mastectomy radiation therapy (PMRT). In the multivariable analysis, the patients who reported being financially uncomfortable or who had ALND were at higher risk of arm swelling at 1 year. Being overweight, receiving ALND after sentinel lymph node biopsy, and receiving PMRT were associated with decreased ROM at 1 year.

CONCLUSION

High rates of self-reported arm morbidity in young breast cancer survivors were reported, particularly in patients receiving ALND and PMRT. Attention to the risks and benefits of differing local therapy strategies for ALND and PMRT patients is warranted.

Clinical Outcomes for Patients With Metastatic Breast Cancer Treated With Immunotherapy Agents in Phase I Clinical Trials

BACKGROUND

Immuno-oncology (IO) agents have demonstrated efficacy across many tumor types and have led to change in standard of care. In breast cancer, atezolizumab and pembrolizumab were recently FDA-approved in combination with chemotherapy specifically for patients with PD-L1-positive metastatic triple-negative breast cancer (TNBC). However, the single agent PD-1/PD-L1 inhibitors demonstrate only modest single agent efficacy in breast cancer. The purpose of this study was to investigate the efficacy of novel IO agents in patients with metastatic breast cancer (MBC), beyond TNBC, treated in phase I clinical trials at the University of Colorado.

METHODS

We performed a retrospective analysis using a database of patients with MBC who received treatment with IO agents in phase I/Ib clinical trials at the University of Colorado Hospital from January 1, 2012 to July 1, 2018. Patient demographics, treatments and clinical outcomes were obtained.

RESULTS

We identified 43 patients treated with an IO agent either as a single agent or in combination. The average age was 53 years; 55.8% had hormone receptor-positive/HER2-negative breast cancer, 39.5% TNBC and 4.7% HER2-positive. Patients received an average of 2 prior lines of chemotherapy (range 0-7) in the metastatic setting. Most patients (72.1%) received IO alone and 27.9% received IO plus chemotherapy. Median progression-free survival (PFS) was 2.3 months and median overall survival (OS) was 12.1 months. Patients remaining on study ≥ 6 months (20.9%) were more likely to be treated with chemotherapy plus IO compared to patients with a PFS < 6 months (77.8% v. 14.7%). No differences in number of metastatic sites, prior lines of chemotherapy, breast cancer subtype, absolute lymphocyte count, or LDH were identified between patients with a PFS ≥ 6 months vs. < 6 months.

CONCLUSIONS

Our phase I experience demonstrates benefit from IO therapy that was not limited to patients with TNBC and confirms improved efficacy from IO agents in combination with chemotherapy. A subset of patients with MBC treated in phase I clinical trials with an IO agent derived prolonged clinical benefit. Predictors of response to immunotherapy in breast cancer remain uncharacterized and further research is needed to identify these factors.

Postpartum breast cancer: mechanisms underlying its worse prognosis, treatment implications, and fertility preservation

Breast cancers that occur in young women up to 5 to 10 years' postpartum are associated with an increased risk for metastasis and death compared with breast cancers diagnosed in young, premenopausal women during or outside pregnancy. Given the trend to delay childbearing, this frequency is expected to increase. The (immuno)biology of postpartum breast cancer is poorly understood and, hence, it is unknown why postpartum breast cancer has an enhanced risk for metastasis or how it should be effectively targeted for improved survival. The poorer prognosis of women diagnosed within 10 years of a completed pregnancy is most often contributed to the effects of mammary gland involution. We will discuss the most recent data and mechanistic insights of the most important processes associated with involution and their role in the adverse effects of a postpartum diagnosis. We will also look into the effect of lactation on breast cancer outcome after diagnosis. In addition, we will discuss the available treatment strategies that are currently being used to treat postpartum breast cancer, keeping in mind the importance of fertility preservation in this group of young women. These additional insights might offer potential therapeutic options for the improved treatment of women with this specific condition.

Real-world evidence from a University Hospital system regarding the uptake of adjuvant pertuzumab and/or neratinib before and after their FDA approval

Purpose

Adjuvant pertuzumab and neratinib are independently FDA-approved for treatment of early-stage HER2-positive breast cancer in combination with or following trastuzumab for one year, respectively. Both agents reduce the risk of recurrence; however, the absolute benefit is modest for many patients with added risk of adverse effects. The purpose of this study was to evaluate the clinical use of adjuvant pertuzumab and neratinib in patients with early-stage HER2-positive breast cancer.

Methods

Patients diagnosed with stage I–III HER2-positive breast cancer treated with trastuzumab at four University of Colorado Health hospitals between July 2016 and April 2019 were identified. Patient demographics, cancer stage, treatment, and administration of pertuzumab and/or neratinib were obtained.

Results

We identified a total of 350 patients who received adjuvant trastuzumab for stage I–III HER2-positive breast cancer; 253 (73.1%) had tumors that were ≥ T2 or node-positive disease. The rate of adjuvant pertuzumab use increased following FDA approval; pertuzumab was administered to the majority of patients with node-positive HER2-positive breast cancer. The use of adjuvant pertuzumab was associated with younger age, premenopausal status, and node-positive disease. Rates of administration of adjuvant neratinib were lower, with only 15.2% of patients receiving this therapy within 3 months of completing adjuvant trastuzumab.

Conclusion

In our cohort of patients treated within a diverse healthcare network, the majority of patients with node-positive HER2-positive breast cancer received adjuvant pertuzumab following FDA approval. The use of adjuvant neratinib was less common, potentially as a result of adverse effects, prolongation of therapy, previous administration of adjuvant pertuzumab, and modest benefit.