Breast conserving surgery combined with radiation therapy offers improved survival over mastectomy in early-stage breast cancer

INTRODUCTION

Landmark trials established equivalent survival regardless of extent of breast surgery in early-stage breast cancer. However, recent studies suggest a survival advantage for breast conserving surgery (BCS) with radiotherapy (BCT). This study assesses the impact of type of surgery on overall survival (OS), breast cancer specific survival (BCSS) and local recurrence (LR) in a modern population-based cohort.

METHODS

Female patients aged ≥18, pT1-2pN0, who had surgery between 2006 and 2016 were identified from Breast Cancer Outcome Unit prospective database. Neoadjuvant chemotherapy patients were excluded. Multivariable Cox regression was used to assess the effect of surgical procedure on OS, BCSS, and LR on cohort with complete data.

RESULTS

BCT was performed in 8422 patients and TM in 4034 patients. The baseline characteristics differed between the groups. Mean follow up was 8.3 years. BCT was associated with increased OS HR 1.37, p < 0.001, BCSS survival HR 1.49, p < 0.001, and similar LR HR 1.00, p > 0.90.

CONCLUSION

This study supports that in early-stage breast cancer, BCT has improved BCSS compared to TM without an increased risk of LR.

Circulating tumour mutation detection in triple-negative breast cancer as an adjunct to tissue response assessment

Circulating tumour DNA (ctDNA) detection via liquid biopsy is an emerging alternative to tissue biopsy, but its potential in treatment response monitoring and prognosis in triple negative breast cancer (TNBC) is not yet well understood. Here we determined the prevalence of actionable mutations detectable in ctDNA using a clinically validated cancer gene panel assay in patients with TNBC, without recurrence at the time of study entry. Sequencing of plasma DNA and validation of variants from 130 TNBC patients collected within 7 months of primary treatment completion revealed that 7.7% had detectable residual disease with a hotspot panel. Among neoadjuvant treated patients, we observed a trend where patients with incomplete pathologic response and positive ctDNA within 7 months of treatment completion were at much higher risk of reduced progression free survival. We propose that a high risk subset of early TNBC patients treated in neoadjuvant therapy protocols may be identifiable by combining tissue response and sensitive ctDNA detection.

Breast-Conserving Therapy is Associated with Improved Survival Without an Increased Risk of Locoregional Recurrence Compared with Mastectomy in Both Clinically Node-Positive and Node-Negative Breast Cancer Patients

INTRODUCTION

Randomized trials demonstrated equivalent survival between breast-conserving surgery combined with radiotherapy (BCT) and mastectomy alone. Contemporary retrospective studies using pathological stage have reported improved survival with BCT. However, pathological information is unknown before surgery. To mimic real-world surgical decision-making, this study assesses oncological outcomes by using clinical nodal status.

METHODS

Female patients aged 18-69 years who were treated with upfront BCT or mastectomy between 2006 and 2016 for T1-3N0-3 breast cancer were identified by using prospective, provincial database. The patients were divided into clinically node-positive (cN+) and node-negative (cN0) strata. Multivariable logistic regression was used to assess the effect of local treatment type on overall survival (OS), breast cancer-specific survival (BCSS), and locoregional recurrence (LRR).

RESULTS

Of 13,914 patients, 8228 had BCT and 5686 had mastectomy. Mastectomy patients had higher-risk clinicopathological factors: pathologically positive axillary staging was 21% in BCT and 38% in mastectomy groups. Most patients received adjuvant systemic therapy. For cN0 patients, 7743 had BCT and 4794 had mastectomy. On multivariable analysis, BCT was associated with improved OS (hazard ratio [HR] 1.37, p < 0.001) and BCSS (HR 1.32, p < 0.001), whereas LRR was not different between the groups (HR 0.84, p = 0.1). For cN+ patients, 485 had BCT and 892 had mastectomy. On multivariable analysis, BCT was associated with improved OS (HR 1.46, p = 0.002) and BCSS (HR 1.44, p = 0.008), whereas LRR was not different between the groups (HR 0.89, p = 0.7).

CONCLUSIONS

In the era of contemporary systemic therapy, BCT was associated with better survival than mastectomy, without an increased risk of locoregional recurrence for both cN0 and cN+ presentations.

Implementation of pharmacogenetic testing in oncology: DPYD-guided dosing to prevent fluoropyrimidine toxicity in British Columbia

Background: Fluoropyrimidine toxicity is often due to variations in the gene (DPYD) encoding dihydropyrimidine dehydrogenase (DPD). DPYD genotyping can be used to adjust doses to reduce the likelihood of fluoropyrimidine toxicity while maintaining therapeutically effective drug levels. Methods: A multiplex QPCR assay was locally developed to allow genotyping for six DPYD variants. The test was offered prospectively for all patients starting on fluoropyrimidines at the BC Cancer Centre in Vancouver and then across B.C., Canada as well as retrospectively for patients suspected to have had an adverse reaction to therapy. Dose adjustments were made for variant carriers. The incidence of toxicity in the first three cycles was compared between DPYD variant allele carriers and non-variant carriers. Subsequent to an initial implementation phase, this test was made available province-wide. Results: In 9 months, 186 patients were tested and 14 were found to be heterozygous variant carriers. Fluoropyrimidine-related toxicity was higher in DPYD variant carriers. Of 127 non-variant carriers who have completed chemotherapy, 18 (14%) experienced severe (grade ≥3, Common Terminology Criteria for Adverse Events version 5.0). Of note, 22% (3 patients) of the variant carriers experienced severe toxicity even after DPYD-guided dose reductions. For one of these carriers who experienced severe thrombocytopenia within the first week, DPYD testing likely prevented lethal toxicity. In DPYD variant carriers who tolerate reduced doses, a later 25% increase led to chemotherapy discontinuation. As a result, a recommendation was made to clinicians based on available literature and expert opinion specifying that variant carriers who tolerated two cycles without toxicity can have a dose escalation of only 10%. Conclusion: DPYD-guided dose reductions were a feasible and acceptable method of preventing severe toxicity in DPYD variant carriers. Even with dose reductions, there were variant carriers who still experienced severe fluoropyrimidine toxicity, highlighting the importance of adhering to guideline-recommended dose reductions. Following the completion of the pilot phase of this study, DPYD genotyping was made available province-wide in British Columbia.

Does age affect outcome with breast cancer?

Prior data about the influence of age at diagnosis of breast cancer on patient outcomes and survival has been conflicting. Using the Breast Cancer Outcomes Unit database at BC Cancer, this retrospective population-based study identified a cohort of 24,469 patients diagnosed with invasive breast cancer between 2005 and 2014. Median follow-up was 11.5 years. We analyzed clinical and pathological features at diagnosis and treatment specific variables compared across the following age cohorts: <35, 35-39, 40-49, 50-59, 60-69, 70-79, and 80 years of age and older. We assessed the impact of age on breast cancer specific survival (BCSS) and overall survival (OS) by age and subtype. There were distinct clinical-pathological and treatment pattern differences at both extremes of age at diagnosis. Patients <35 and 35-39 years old were more likely to present with higher risk features, HER2 positive or triple-negative biomarkers, and more advanced TNM stage at diagnosis. They were more likely to undergo treatment with mastectomy, axillary lymph node dissection, radiotherapy and chemotherapy. Conversely, patients ≥80 years old were generally more likely to have hormone-sensitive HER2-negative disease, and lower TNM stage at diagnosis. They were less likely to undergo surgery or be treated with radiotherapy and chemotherapy. Both younger and elderly age at breast cancer diagnosis were independent risk factors for poorer prognosis after controlling for subtype, LVI, stage, and treatment factors. This work will help clinicians to more accurately estimate patient outcomes, patterns of relapse, and provide evidence-based treatment recommendations.

Personalizing Adjuvant Endocrine Therapy for Early-Stage Hormone Receptor-Positive Breast Cancer

Endocrine therapy has undergone major changes in the past few years, and is no longer a "one- size- fits- all" prescription. This article discussed some of the new developments and directions.

Abstract P4-07-04: Bc cancer ipsilateral breast tumor recurrence (BCC IBTR) nomogram

INTRODUCTION:. Local and systemic treatments for breast cancer have evolved in the past decades. This study reports the development of a modern population-based nomogram to individualize local recurrence (LR) risk estimates for patients treated with breast conservation surgery (BCS). The magnitude of benefit of adjuvant breast radiotherapy (BRT) depends on individual patient, tumor, and treatment characteristics (1). Nomograms can provide accurate predictions of LR and the absolute LR benefit of BRT that can assist patients in making informed decisions regarding BRT. This nomogram is based on a large cohort of women with prospectively captured biomarker data and modern systemic therapies including anti-human epidermal growth factor receptor 2 (HER2) therapy. METHOD:. Study Population:. The study cohort included women treated curatively for newly diagnosed breast cancer between 1st January 2005 and 31st December 2014. Inclusion criteria were: age &gt;16 years, invasive ductal or lobular carcinoma, stage I-III, and BCS. Patients with metastatic disease, prior or synchronous contralateral breast cancer, unknown tumor or treatment characteristics, or treated with neoadjuvant therapy or mastectomy were excluded. Nomogram Development and Validation:. Age, tumor size, number of positive lymph nodes, grade, margin status, lymphovascular invasion (LVI), extensive intraductal component (EIC), estrogen receptor (ER), progesterone receptor (PR), HER2 status, use of chemotherapy, hormonal therapy, and radiotherapy with or without boost were recorded for each patient. The endpoint was LR as the first event. Fine and Gray’s competing risk model, with distant recurrence and death as competing risks, was used for the multivariable analysis, adjusting for demographics, tumor, and treatment factors. Hazard ratio (HR) and 95% confidence interval (CI) for each variable were calculated. The multivariable model forms the basis for the nomogram, which is being internally validated using the bootstrap and cross-validation. RESULTS:Of 11,310 patients, there were 429 LR (crude risk = 3.8%). The HR and 95% CIs from the Fine and Gray model for each of the variables in the nomogram are presented in the table. Age, number of positive nodes, grade, ER, LVI, margins, hormone therapy, chemotherapy, and radiotherapy were independent prognostic factors for LR. For patients treated with RT, the predicted 10-year cumulative incidence of LR ranged from 2.4% in patients with low-risk disease to 12.5% in patients with high-risk disease. CONCLUSION:A new nomogram for local recurrence, based on patients who had ER/PR/HER2 testing and who received modern systemic therapies is being developed. It will assist clinicians and patients individualize estimates of local recurrence risk and improve shared decision-making regarding the use of BRT in contemporary practice. REFERENCES:. (1)Sanghani, M., et al J Clin Oncol.,2010; 28(5), 718-722.

Cox regression hazard ratios and confidence intervals for variablesCharacteristicHR95%CIp-valueAge0.980.970.99&lt;0.01T-size1.011.001.010.14No. nodes1.041.011.070.005GradeGrade1---Grade21.751.322.33&lt;0.001Grade32.541.813.56&lt;0.001ERNeg---Pos1.441.012.060.046PRNeg---Pos0.790.611.030.084Her2Neg---Pos0.960.731.250.8LVINeg---Pos1.961.552.47&lt;0.001Unk1.360.722.580.3Margin StatusNeg---Close1.411.081.840.011Pos1.681.082.590.200Extensive DCISNo---Yes1.140.841.550.4HTNo---Yes0.520.410.65&lt;0.001ChemoNo---Yes0.540.420.71&lt;0.001RTNo---Yes0.330.260.42&lt;0.001BoostNo---Yes0.800.621.040.094

Citation Format: Dylan Narinesingh, Alan Nichol, Pauline Truong, Lovedeep Gondara, Caroline Speers, Laveniya Kugathasan, Caroline Lohrisch, Dave Voduc, Nafisha Lalani. Bc cancer ipsilateral breast tumor recurrence (BCC IBTR) nomogram [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-07-04.

Abstract P4-11-08: Impact of ovarian stimulation for fertility preservation in young women with breast cancer: Updated survival and pregnancy outcomes

Background: Chemotherapy (CTx) and hormone therapy may impair fertility in women with breast cancer (BC) by direct gonadotoxicity or delayed childbearing. Inconsistent data regarding the safety and efficacy of ovarian stimulation for fertility preservation (FP) in BC may limit clinician referral and patient uptake of FP. We previously examined the effect of FP on BC recurrence and herein present updated survival and pregnancy outcomes in relation to FP from an expanded BC cohort. Methods: Women aged ≤ 40 years diagnosed with stage I-III BC between 2007-2018 referred to one of six cancer centres and to a reproductive endocrinologist in British Columbia, Canada were identified from a central database. Clinicopathologic, treatment and outcome characteristics were compared using uni/multivariate Cox and logistic regression analyses for survival and pregnancy outcomes, respectively, for patients who did and did not undergo FP prior to systemic cancer treatment. Results: 158 patients were identified. Sixty-four (41%) had lymph node involvement, 119 (75%) had ER-positive and 39 (25%) had HER2-positive BC. The 72 (46%) patients who underwent FP were more likely to be younger (mean age 33 vs 34 y, p=0.030), ECOG 0 (p=0.013), have CTx (p&lt;0.001) and GnRH agonist during CTx (p=0.010) compared to patients with no FP. Tumor stage, ER/HER2/BRCA-positivity, BMI, radiation and number of existing children were not associated with decision to pursue FP (p&gt;0.05). After a median follow-up of 4.7 years, BC recurrence occurred in 15 (17%) non-FP patients and 9 (13%) FP patients (Table 1). FP did not affect overall survival by univariate (HR 0.9; 95% CI 0.7-1.3) or multivariate analysis controlling for age, BMI, ECOG/ER/HER2 status, tumor stage and receipt of CTx or radiation (HR 1.0, 95% CI 0.7-1.4). Post-diagnosis, 22 (31%) FP patients and 11 (13%) non-FP patients had ≥ 1 pregnancy (Table 2). The use of assisted reproductive technology (ART) was similar in both groups. Patients who had FP were 2.8 times more likely (p=0.013) to conceive at least once. The results remained significant on multivariate analysis controlling for age, BMI, ECOG status and baseline parity (p=0.030). Non-FP patients had a 31% higher miscarriage rate than those who did (p=0.26). Conclusions: FP was not associated with an increased risk of locoregional recurrence, distant recurrence or death over a follow-up period of 3-11 years, supporting its safety in young women with BC. Despite more often receiving CTx, patients who underwent FP were significantly more likely to conceive after BC than those who did not, even when accounting for differences in patient profiles. This may relate to greater use of GnRH agonists during CTx, known to protect ovarian function, and stronger desires for future childbearing in patients who pursued FP. Although there was similar use of ART in both groups, the higher pregnancy rate and more successful reproductive outcomes in FP patients support the value and promotion of pre-oncologic treatment FP in young BC patients early in their disease trajectory, to enhance survivorship family planning.

Table 1.Survival outcomes of patients.CharacteristicNo FP (n=86)FP (n=72)p-valueRecurred [n (%)]0.85Locoregional6 (7)4 (6)Distant9 (10)5 (7)Deceased [n (%)]8 (9)4 (6)0.38

Table 2.Characteristics of first pregnancies in patients conceiving after diagnosis.CharacteristicNo FP (n=11)FP (n=21)p-valuePregnancy outcome [n (%)]0.26Completed3 (27)11 (52)Miscarriage7 (64)7 (33)Ongoing1 (9)3 (14)Pregnancy interval from diagnosis [n (%)]0.29≤ 2 y04 (19)2-5 y8 (73)13 (62)&gt; 5 y3 (27)4 (19)Type of conception [n (%)]0.52Natural9 (82)15 (71)Assisted2 (18)6 (29)

Citation Format: Megan E Tesch, Ying Wang, Chloe Lim, Ying Hui Xu, Shaina Lee, Kirstin Perdrizet, Dan Yokom, Ellen Warner, Jeffrey Roberts, Caroline Lohrisch. Impact of ovarian stimulation for fertility preservation in young women with breast cancer: Updated survival and pregnancy outcomes [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-11-08.

Association between regional nodal irradiation and breast cancer recurrence-free interval for patients with low-risk, node-positive breast cancer

PURPOSE/OBJECTIVE(S)

Randomized clinical trials have shown that regional nodal irradiation (RNI) in patients with unselected N1 breast cancer improves breast cancer-specific survival. However, the benefit of RNI in women with biologically low risk, N1 breast cancer is uncertain. We conduct a population-based study to determine if RNI is associated with improved breast cancer recurrence-free interval (BCRFI) in this population.

MATERIALS/METHODS

Patients aged 40-79 with pT1-2pN1 (node-positive) breast cancers diagnosed from 2005 to 2014 were identified. Inclusion criteria were modeled off the TAILOR RT study, which is a randomized non-inferiority clinical trial designed to assess the value of RNI in low-risk N1 patients. Eligible patients had BCS (breast-conserving surgery) or mastectomy & axillary lymph node dissection (ALND) with 1-3 positive nodes, BCS and sentinel lymph node biopsy (SLNB) with 1-2 positive nodes, or mastectomy and SLNB with 1 positive node. Additionally, patients had Luminal A breast cancers, as approximated by: estrogen receptor positive (Allred 6-8/8), progesterone receptor positive (Allred 6-8/8), human epidermal growth factor receptor 2 (HER2)-negative, and grade 1-2 immunohistochemical testing. All patients were prescribed hormonal treatment. The primary endpoint of BCRFI, which was the time to any breast cancer recurrence or breast cancer-related death, was analyzed using multivariate competing risks analysis.

RESULTS

The cohort included 1,169 women with a median follow-up of 9.2 years. Radiation treatments were: none (151 treated with mastectomy alone), breast-only (133) and locoregional (885). Patients undergoing RNI were younger (median 58 versus 62 years), more likely to have 2-3 macroscopic lymph nodes involved and more often received chemotherapy (all p<0.05). The 10-year estimate of BCRFI was 90% without RNI versus 90% with RNI (p=0.5). On multivariable analysis, RNI was not a significant predictor of BCRFI (HR=1.0, p=0.9).

CONCLUSION

In this retrospective analysis, RNI was not associated with improved BCRFI for women with biologically low risk, N1 breast cancer. We advocate accrual to the ongoing TAILOR RT study.

Sentinel Node Biopsy Should Not be Routine in Older Patients with ER-Positive HER2-Negative Breast Cancer Who Are Willing and Able to Take Hormone Therapy

BACKGROUND

The SSO Choosing Wisely campaign recommended selective sentinel lymph node biopsy (SLNB) in clinically node-negative women aged ≥ 70 years with ER+ breast cancer. We sought to assess the association of SLNB positivity, adjuvant treatment, and survival in a population-based cohort.

PATIENTS AND METHODS

Women aged ≥ 70 years treated for ER+ HER2- breast cancer between 2010 and 2016 were identified in our prospective provincial database. Overall survival (OS) and breast cancer-specific survival (BCSS) were assessed using Kaplan-Meier analysis. Multivariable logistic regression was used to assess the association of SLNB positivity with use of adjuvant treatments and survival outcomes.

RESULTS

We identified 2662 patients who met study criteria. SLNB was positive in 25%. Increased use of chemotherapy (ChT), hormone therapy (HT), and radiotherapy (RT) was significantly associated with SLNB positivity. Five-year OS was 86%, and BCSS was 96% with median follow-up of 4.3 years. BCSS was worse with grade 3 disease (HR 4.1, 95% CI 2.1-8.1, p < 0.0001) and better with HT (HR 0.5 95% CI 0.3-0.9, p = 0.01). Patients with a positive SLNB treated without adjuvant therapy had lower BCSS (HR 3.2 95% CI 1.2-8.4, p = 0.017) than those with a negative SLNB, but patients with a positive SLNB treated with any combination of ChT, HT, and/or RT, had similar BCSS to those with a negative SLNB.

CONCLUSIONS

BCSS in this population was excellent at 96%, and BCSS was similar with negative and positive SLNB when patients received HT. SLNB can be omitted in elderly patients willing to take HT.

The cost-effectiveness of adding tomosynthesis to mammography-based breast cancer screening: an economic analysis

BACKGROUND

Observational studies show that digital breast tomosynthesis (DBT) combined with digital mammography (DM) can reduce recall rates and increases rates of breast cancer detection. The objective of this study was to examine the cost-effectiveness of DBT plus DM versus DM alone in British Columbia and to identify parameters that can improve the efficiency of breast cancer screening programs.

METHODS

We conducted an economic analysis based on data from a cohort of screening participants in the BC Cancer Breast Screening Program. The decision model simulated lifetime costs and outcomes for participants in breast cancer screening who were aged 40-74 years between 2012 and 2017. We analyzed rates of health care resource utilization, health state costs and estimated incremental cost-effectiveness ratios (ICERs), to measure incremental cost differences per quality-adjusted life years (QALYs) gained from the addition of DBT to DM-based screening, from the government payer's perspective.

RESULTS

The model simulated economic outcomes for 112 249 screening participants. We found that the ICER was highly sensitive to recall rate reductions and insensitive to parameters related to cancer detection. If DBT plus DM can reduce absolute recall rates by more than 2.1%, the base-case scenario had an ICER of $17 149 per QALY. At a willingness-to-pay threshold of $100 000 per QALY, more than 95% of the probabilistic simulations favoured the adoption of DBT plus DM versus DM alone. The ICER depended heavily on the ability of DBT plus DM to reduce recall rates.

INTERPRETATION

The addition of DBT to DM would be considered cost-effective owing to the low positive predictive value of screening with DM alone. Reductions in false-positive recall rates should be monitored closely.

Abstract PS4-26: Impact of TAILORx data on chemotherapy prescribing in British Columbia

Background: Developed with retrospective data, the 21-gene recurrence score assay (RS) reduces adjuvant chemotherapy (CTx) use in hormone-positive (HR+), HER2-negative, node-negative breast cancer, justifying the assay’s cost. The TAILORx trial prospectively confirmed the predictive value of RS and established thresholds for CTx benefit in younger and older patients. We examined CTx use in British Columbia (BC) following TAILORx publication, as a prelude to exploring age-adjusted cost effectiveness of the assay.

Methods: We assembled 3 cohorts of patients with HR+, HER2-negative, node-negative breast cancer: diagnosed before RS funding (cohort 1: January 1, 2013-December 31, 2013), after introduction of public funding (cohort 2: July 1, 2015-June 30, 2016), and after TAILORx results (cohort 3: July 1, 2018-June 30, 2019). Patients aged 18-80 years with tumors that were grade 3, grade 2 T1b or larger, or any T size and grade if ≤ 40 years of age were included, matching BC funding criteria. Previous in situ or invasive breast cancer cases were excluded. CTx use by age and RS was compared between cohorts using univariate analyses.

Results: 2,066 patients met inclusion criteria (Table 1). CTx use in cohorts 1, 2, and 3 was 21%, 17%, and 13%, respectively. In cohorts 2 plus 3, CTx use was 30% for patients up to 50 years of age and 11% for patients over 50 years of age. Baseline characteristics were balanced, except grade 3 histology (24%, 25%, 17% in cohorts 1, 2, 3, respectively; p=0.01). RS was ≥ 26 in 33% of grade 3 and 34% of PR negative tumors. CTx use declined by 19% after RS funding was introduced and by another 23% after TAILORx publication (p=0.001). Reduction in CTx use was significant for RS 11-20 tumors (cohort 3 vs. 2, p=0.004). A 7.5% nonsignificant increase in CTx was seen for RS 26-30 tumors (cohort 2 vs. 3, p=0.55). There was no significant change in CTx use in patients aged &gt; 50 years (12% in cohort 2 vs. 10% in cohort 3, p=0.22). Among patients aged 70-80 years in cohort 3 with RS, 5% had RS ≥ 26, and of these, 40% had CTx (9% of patients in this age group), compared with 92% CTx use for patients aged ≤ 50 years with RS ≥ 26 (15% of patients in this age group).

Conclusions: CTx use decreased after TAILORx publication, particularly for RS 11-20 tumors. CTx use changed less in patients over 50 years old, suggesting that trial results confirmed pre-existing prescribing practices. CTx use increased in patients with RS 26-30 tumors, reflecting acceptance of the new threshold for CTx benefit established by TAILORx. CTx use was low overall in patients aged &gt; 50 years, especially in those aged 70-80 years, in part due to the very low frequency of high RS tumors. Given these findings, we conclude that cost effectiveness modelling for publicly funded RS should take age into consideration.

Table 1: Receipt of adjuvant chemotherapy (CTx) by 21-gene recurrence score (RS) result before assay availability (cohort 1), after assay availability (cohort 2), and after TAILORx publication (cohort 3) in patients (pts) aged ≤ 50 (a) and 51-80 years (b).a)Age≤ 50, n = 423Cohort123No. of pts who received CTx / No. of pts in group (%)RS not done51/105 (48.6)28/56 (50)1/6 (16.7)RS ≤ 101/5 (20.0)0/17 (0)1/25 (4.0)RS 11-201/8 (12.5)4/52 (7.7)2/67 (3.0)RS 21-251/3 (33.3)8/17 (47.1)10/20 (50.0)RS 26-300/0 (0)5/5 (100)5/5 (100)RS ≥ 312/2 (100)10/11 (90.9)17/19 (89.5)Entire cohort56/123 (45.5)55/158 (34.8)36/142 (25.4)b)Age51-80, n = 1643Cohort123No. of pts who received CTx / No. of pts in group (%)RS not done72/494 (14.6)25/279 (9.0)2/86 (2.3)RS ≤ 100/6 (0)0/60 (0)0/110 (0)RS 11-202/11 (18.2)5/126 (4.0)0/198 (0)RS 21-252/5 (40.0)6/56 (10.7)2/64 (3.1)RS 26-302/3 (66.7)5/20 (25.0)14/35 (40.0)RS ≥ 312/2 (100)31/40 (77.5)37/48 (77.1)Entire cohort80/521 (15.4)72/581 (12.4)55/541 (10.2)

Citation Format: Megan Tesch, Caroline Speers, Rekha Manhas Diocee, Alan Nichol, Caroline Lohrisch. Impact of TAILORx data on chemotherapy prescribing in British Columbia [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-26.

Abstract PD4-02: Sentinel node biopsy should not be routine in older patients with ER positive breast cancer

Background:Based on randomized controlled trials demonstrating no survival benefit of axillary dissection in elderly breast cancer patients, the SSO/Choosing Wisely campaign recommended against the routine use of sentinel lymph node biopsy (SLNB) in clinically node negative patients aged ≥70 with estrogen receptor (ER) positive breast cancer in 2016. SLNB is still performed in &gt;80% of such patients and we have previously shown that at our institution, SLNB positivity influences adjuvant therapy decisions in this population. In this study, we sought to validate the association of SLNB positivity and adjuvant treatment in a larger population-based cohort, and to evaluate the impact of this finding on oncologic outcomes.

Methods:The Breast Cancer Outcome Unit (BCOU) prospectively collects demographic, pathologic, treatment and outcomes data on all patients referred to BC Cancer with breast cancer in British Columbia, Canada. Female patients aged ≥70 with newly diagnosed estrogen receptor-positive invasive breast cancer who underwent SLNB from 2010-2016 were included. Patients with HER2-positive disease or those treated with neoadjuvant therapy were excluded. Multivariable analysis was used to assess the effect of SLNB positivity on adjuvant treatment. Overall survival (OS) and breast cancer specific survival (BCSS) were assessed using Kaplan-Meier analysis and Cox regression was used to assess contribution of SLNB positivity and adjuvant treatment. A nomogram was created to model the effect of nodal positivity and adjuvant treatment on BCSS.

Results:We identified 2580 patients who met study criteria with a median age of 75 and a median tumor size of 15 mm. SLNB was positive in 23%. Sixty-seven percent of patients had breast conserving surgery (BCS) and 62% of patients had RT (BCS 79%, mastectomy 25%). As systemic therapy 5% of patients had chemotherapy (CT) and 78% of patients had hormone therapy (HT). Use of adjuvant therapies was associated with SLNB positivity: Systemic therapy (HR = 2.4, 95% CI: 1.84-3.14, p &lt;0.0001), RT (HR = 4.94, 95% CI: 3.91-6.25, p &lt;0.0001) and nodal RT (HR = 61.4, 95% CI: 26.6-141.7, p &lt;0.0001). The 5-year OS was 86% and BCSS was 96% with a median follow-up of 4.33 years (95% CI 4.21-4.47 years). There was improved BCSS with receipt of HT (HR 0.51 95% CI 0.301-0.875, p=0.0142) and worse BCSS with grade 3 vs grade 1 disease (HR 4.09, 95% CI 2.06-8.10, p&lt;0.0001). Age, tumor size, status of SLNB and use of RT were not significant prognostic variables. Patients with a positive SLNB who did not receive any adjuvant therapy had lower BCSS (HR 3.22 95% CI 1.235-8.418, p=0.0168) than those with a negative SLNB. However, amongst those who received any combination of CT, HT and RT, there was no significant difference in BCSS regardless of nodal status. A nomogram was developed incorporating tumor size, grade, SLNB status and adjuvant treatment. Using the nomogram, patients aged 75-79 with T1, grade 1-2 tumors, with or without positive SLNB and treated with or without adjuvant therapy had 5-year BCSS ≥95%. The nomogram also indicated that 5-year BCSS was similar for patients with positive and negative SLNB for all combinations of tumor features when patients received HT.

Conclusions:In this modern, population-based cohort of patients over 70 with ER-positive breast cancer, 5-year BCSS was excellent at 96%. Although the use of adjuvant treatment was associated with a positive SLNB, BCSS was not changed based on nodal status when patients received HT. Our results support the Choosing Wisely recommendations; SLNB can be safely omitted in elderly patients willing to take HT, and we advocate that SLNB can be omitted in low-risk patients aged ≥75 even in the absence of planned HT.

Citation Format: Elaine McKevitt, Rona Cheifetz, Kimberly DeVries, Alison Laws, Rebecca Warburton, Lovedeep Gondara, Caroline Lohrisch, Alan Nichol. Sentinel node biopsy should not be routine in older patients with ER positive breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PD4-02.

Efficacy and Safety of Trastuzumab Emtansine Plus Capecitabine vs Trastuzumab Emtansine Alone in Patients With Previously Treated ERBB2 (HER2)-Positive Metastatic Breast Cancer: A Phase 1 and Randomized Phase 2 Trial

Question

What is the effect of adding capecitabine to trastuzumab emtansine (T-DM1) treatment in patients with previously treated ERBB2 (HER2)-positive metastatic breast cancer?

Findings

In this phase 1/2 randomized clinical trial of 161 patients with previously treated ERBB2-positive metastatic breast cancer, the overall response rate was 44% and 36% in the combination and single-agent T-DM1 arms, respectively; median overall survival was not estimable and 24.7 months. Adverse events occurred in 95% (grade 3-4: 44%) and 89% (grade 3-4: 41%) of patients in each arm, respectively.

Meaning

Adding capecitabine to T-DM1 increases toxic effects and does not improve clinical outcomes vs T-DM1 alone for previously treated ERBB2-positive metastatic breast cancer.

Importance

ERBB2 (HER2)-targeted therapy provides benefits in metastatic breast cancer (mBC) and gastric cancer, but additional treatments are needed to maximize efficacy and quality of life.

Objective

To determine maximum tolerated doses (MTDs) of trastuzumab emtansine (T-DM1) plus capecitabine in patients with previously treated ERBB2-positive mBC and locally advanced/metastatic gastric cancer (LA/mGC) (phase 1) and the efficacy and safety of this combination vs T-DM1 alone in patients with mBC (phase 2).

Design, Setting, and Participants

The MTD in phase 1 was assessed using a 3 + 3 design with capecitabine dose modification. Phase 2 was an open-label, randomized, international multicenter study of patients with mBC treated with T-DM1 plus capecitabine or T-DM1 alone. Eligible patients had previously treated ERBB2-positive mBC or LA/mGC with no prior chemotherapy treatment for advanced disease.

Interventions

Patients in the phase 1 mBC cohort received capecitabine (750 mg/m², 700 mg/m², or 650 mg/m² twice daily, days 1-14 of a 3-week cycle) plus T-DM1 3.6 mg/kg every 3 weeks. Patients with LA/mGC received capecitabine at the mBC phase 1 MTD, de-escalating as needed, plus T-DM1 2.4 mg/kg weekly. In phase 2, patients with mBC were randomized (1:1) to receive capecitabine (at the phase 1 MTD) plus T-DM1 or T-DM1 alone.

Main Outcomes and Measures

The phase 1 primary objective was to identify the MTD of capecitabine plus T-DM1. The phase 2 primary outcome was investigator-assessed overall response rate (ORR).

Results

In phase 1, the median (range) age was 54.0 (37-71) and 57.5 (53-70) years for patients with mBC and patients with LA/mGC, respectively. The capecitabine MTD was identified as 700 mg/m² in 11 patients with mBC and 6 patients with LA/mGC evaluable for dose-limiting toxic effects. In phase 2, between October 2014 and April 2016, patients with mBC (median [range] age, 52.0 [28-80] years) were randomized to receive combination therapy (n = 81) or T-DM1 (n = 80). The ORR was 44% (36 of 81 patients) and 36% (29 of 80 patients) in the combination and T-DM1 groups, respectively (difference, 8.2%; 90% CI, −4.5 to 20.9; P = .34; clinical cutoff, May 31, 2017). Adverse events (AEs) were reported in 78 of 82 patients (95%) in the combination group, with 36 (44%) experiencing grade 3-4 AEs, and 69 of 78 patients (88%) in the T-DM1 group, with 32 (41%) experiencing grade 3-4 AEs. No grade 5 AEs were reported.

Conclusions and Relevance

Adding capecitabine to T-DM1 did not statistically increase ORR associated with T-DM1 in patients with previously treated ERBB2-positive mBC. The combination group reported more AEs, but with no unexpected toxic effects.

Trial Registration

ClinicalTrials.gov Identifier: NCT01702558

Breast Cancer Molecular Subtype as a Predictor of Radiation Therapy Fractionation Sensitivity

PURPOSE

The predictive benefit of breast cancer molecular subtypes for systemic therapy approaches has been well established; yet, there is a paucity of data regarding their use as a predictor of radiation therapy fractionation sensitivity. The purpose of this study was to determine whether rates of local recurrence (LR) for patients treated with hypofractionated (HF) radiation therapy, in comparison to conventional fractionation, differ across breast cancer molecular subtypes in a large, prospectively collected cohort treated with modern systemic therapy.

METHODS AND MATERIALS

Patients who received a diagnosis of stage I-III breast cancer between 2005 and 2009 were identified. Molecular subtype was determined using the American Joint Committee on Cancer classification system (luminal-A, luminal-B, HER2+, triple negative [TN]). Multivariable Cox regression modeling was used to identify predictors of LR. LR-free-survival (LRFS) was determined using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

A total of 5868 cases were identified with a median follow-up of 10.8 years. Patients with luminal-A subtype composed 45% of the cohort (n = 2628), compared with 30% luminal-B (n = 1734), 15% HER2+ (n = 903), and 10% TN (n = 603). A total of 76% (n = 4429) of patients were treated with HF. The 10-year LRFS was 97.1% (95% confidence interval [CI], 96.6-97.6) for the whole cohort. The 10-year LRFS based on molecular subtypes was 98.3% (95% CI, 97.6-98.7) luminal-A, 96.6% (95% CI, 95.5-97.4) luminal-B, 97.0% (95% CI, 95.5-98.0) HER2+, and 93.5% (95% CI, 91.1-95.3) TN (P < .001). There was no difference in the 10-year LRFS between patients treated with HF versus conventional fractionation among those with luminal-A (98.2% vs 98.4%; P = .42), luminal-B (96.6% vs 96.8%; P = .90), HER2+ (97.5% vs 95.8%; P = .12), or TN (93.9% vs 92.2%; P = .47). There was no significant interaction between subtype and fractionation regimen.

CONCLUSIONS

These data support the routine use of hypofractionated radiation therapy regimens across all breast cancer subtypes.

Hypofractionated Adjuvant Radiation Therapy Is Effective for Patients With Lymph Node-Positive Breast Cancer: A Population-Based Analysis

PURPOSE

This study evaluated long-term, population-based, breast cancer-specific outcomes in patients treated with radiation therapy (RT) to the breast/chest wall plus regional nodes using hypofractionated (HF) (40-42.5 Gy/16 fractions) versus conventionally fractionated (CF) regimens (50-50.4 Gy/25-28 fractions).

METHODS AND MATERIALS

A prospective provincial database was used to identify patients with lymph node-positive breast cancer treated with curative-intent breast/chest wall + regional nodal RT from 1998 to 2010. The effect of RT fractionation on locoregional recurrence-free survival (LRRFS), distant recurrence-free survival (DRFS), and breast cancer-specific survival (BCSS) was assessed for the entire cohort and for high-risk subgroups: grade 3, ER-/HER2-, HER2+, and ≥4 positive nodes. Multivariable analysis and 2:1 case-match comparison of HF versus CF were also performed.

RESULTS

A total of 5487 patients met the inclusion criteria (4006 HF and 1481 CF). Median age was 55 years, and median follow-up was 12.7 years. On multivariable analysis, no statistically significant differences were identified in 10-year LRRFS (hazard ratio [HR] 0.87; 95% confidence interval [CI], 0.59-1.27; P = .46), DRFS (HR 0.90; 95% CI, 0.76-1.06; P = .19), or BCSS (HR 0.92; 95% CI, 0.76-1.10; P = .36) between the HF and CF cohorts. There was no statistical difference in breast cancer-specific outcomes in the high-risk subgroups. On analysis of 2962 HF cases matched to 1481 CF controls, no statistical difference was observed in LRRFS (HR 0.98; 95% CI, 0.71-1.33; P = .87), DRFS (HR 0.97; 95% CI, 0.85-1.11; P = .68), or BCSS (HR 1.00; 95% CI, 0.87-1.16; P = .92).

CONCLUSIONS

This large, population-based analysis with long-term follow-up after locoregional RT demonstrated that modest HF provides similar breast cancer-specific outcomes compared with CF. HF is an effective option for patients with stage I to III breast cancer receiving nodal RT.

Impact of Recurrence Score on type and duration of chemotherapy in breast cancer

Background

The use of Oncotype dx (Genomic Health, Redwood City, CA, U.S.A.) testing has been shown to change treatment decisions in approximately 30% of breast cancer (bca) cases, but research on how Recurrence Score testing has affected the type of chemotherapy offered is limited. We sought to determine if the availability of Oncotype dx testing resulted in a change to the type and duration of chemotherapy regimens used in the treatment of early-stage hormone receptor-positive bca.

Methods

In a population-based cohort study, patients treated in the 2 years before the availability of Oncotype dx testing were compared with patients treated in the 2 years after testing availability. Charts were audited and divided into 2 groups: pre-Oncotype dx and post-Oncotype dx. The groups were compared for differences in duration of chemotherapy (12 weeks vs. >12 weeks), types of agents used (anthracycline vs. non-anthracycline), and myelosuppressive potential of the chosen regimen.

Results

Of 834 patients who fulfilled the enrolment criteria, 360 fell into the pre-Oncotype dx era, and 474, into the post-Oncotype dx era. An increase of 11.2 percentage points, to 69.5% from 58.3%, was observed in the proportion of patients receiving short-course compared with long-course chemotherapy (p = 0.068). The proportion of patients prescribed anthracycline-containing regimens declined in the post-Oncotype dx era (47.7% pre vs. 32.2% post, p = 0.016). The selection of more-myelosuppressive chemotherapy protocols increased in the post-Oncotype dx era (67.4% pre vs. 78.8% post, p = 0.044).

Conclusions

In the present study, the availability of Oncotype dx testing was observed to influence the choice of chemotherapy type in the setting of early-stage bca.

The impact of new systemic therapies on survival and time on hormonal treatment in hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer: A population-based study in British Columbia from 2003 to 2013

BACKGROUND

The purpose of this study was to determine whether new systemic therapy regimens have resulted in improved survival and increased time on first- and second-line hormonal treatment for patients with hormone receptor (HR)-positive metastatic breast cancer (MBC) over time.

METHODS

Patients diagnosed with HR-positive, human epidermal growth factor receptor 2 (HER2)-negative MBC were identified across 3 time cohorts (2003-2005, 2007-2009, and 2011-2013). Data were prospectively collected. Cases with previous, synchronous, or subsequent contralateral breast cancer were excluded. The types of first- and second-line therapies, the times on first- and second-line hormonal treatment, and the median survival times were compared across the cohorts.

RESULTS

Within the time period analyzed, 9 new adjuvant systemic therapies (with or without neoadjuvant therapy) and 2 metastatic systemic therapies were approved at BC Cancer for the treatment of HR-positive, HER2-negative MBC. In the 3 time cohorts, 3953 patients diagnosed with MBC were identified. Among the 2432 patients (62%) who had HR-positive/HER2-negative disease, 2197 (90%) received at least 1 line of systemic therapy after the diagnosis of MBC, and 80% of these patients (1752 of 2197) received first- and/or second-line hormonal treatment. The median duration on hormonal treatment was 9.0 months for the first line and 6.1 months for the second line. The durations were similar across the time cohorts (range for the first line, 8.9-9.0 months; range for the second line, 6.0-6.1 months). The median survival for the entire study population was 2.0 years (95% confidence interval, 1.8-2.1 years), and there was no significant difference between the cohorts (range, 1.9-2.0 years).

CONCLUSIONS

Even though more adjuvant and metastatic systemic therapies have been approved since 2003, population-level gains in survival and the time on hormonal treatment for patients with HR-positive, HER2-negative MBC have not been made over the course of a decade.

Do surgeons convey all the details? A provincial assessment of operative reporting for breast cancer

INTRODUCTION

A breast cancer synoptic operative report was developed using a modified Delphi process METHODS: Data from the British Columbia Cancer Breast Cancer Outcomes Unit (BCOU) was used to analyze the association between the completion of a synoptic operative report and reporting of operative details and The American Society of Breast Surgeons quality indicators.

RESULTS

3662 patients had surgery for breast cancer by 185 surgeons. 2281 reports were narrative and 1007 synoptic. Requested surgical details were more commonly reported with synoptic reports for both posterior (96 vs 58%, p < 0.0001) and anterior margins (96 vs 5%, p < 0.0001). This was true for high and low volume surgeons. Quality Indicators were higher in those cases with an associated synoptic report for high and low volume surgeons.

CONCLUSION

Communication of operative details is improved with synoptic reporting. Investment in platforms to facilitate synoptic reporting could improve patient care through improved multidisciplinary communication.

Base excision repair deficiency signatures implicate germline and somatic MUTYH aberrations in pancreatic ductal adenocarcinoma and breast cancer oncogenesis

We report a case of early-onset pancreatic ductal adenocarcinoma in a patient harboring biallelic MUTYH germline mutations, whose tumor featured somatic mutational signatures consistent with defective MUTYH-mediated base excision repair and the associated driver KRAS transversion mutation p.Gly12Cys. Analysis of an additional 730 advanced cancer cases (N = 731) was undertaken to determine whether the mutational signatures were also present in tumors from germline MUTYH heterozygote carriers or if instead the signatures were only seen in those with biallelic loss of function. We identified two patients with breast cancer each carrying a pathogenic germline MUTYH variant with a somatic MUTYH copy loss leading to the germline variant being homozygous in the tumor and demonstrating the same somatic signatures. Our results suggest that monoallelic inactivation of MUTYH is not sufficient for C:G>A:T transversion signatures previously linked to MUTYH deficiency to arise (N = 9), but that biallelic complete loss of MUTYH function can cause such signatures to arise even in tumors not classically seen in MUTYH-associated polyposis (N = 3). Although defective MUTYH is not the only determinant of these signatures, MUTYH germline variants may be present in a subset of patients with tumors demonstrating elevated somatic signatures possibly suggestive of MUTYH deficiency (e.g., COSMIC Signature 18, SigProfiler SBS18/SBS36, SignatureAnalyzer SBS18/SBS36).

Abstract P1-16-05: Prognosis and survival in metastatic breast cancer – Ten years in review, a population-based analysis

Background: The rapidly evolving landscape of systemic treatment for metastatic breast cancer (MBC) during the 1990s led to meaningful improvements in the overall survival (OS) of MBC patients[1]. Despite ongoing and expanded access to new treatments, it remains unclear if this has translated into further advances in survival. Moreover, the prognosis of MBC patients based on subtype, over time, are also important to differentiate.

Methods: The BC Cancer Breast Cancer Outcomes Unit (BCOU) database was utilized to identify patients referred to BC Cancer who were diagnosed with MBC during 3 time cohorts (cohort 1:2003-2005; cohort 2:2007-2009; cohort 3:2011-2013), to reflect changes in MBC treatment over these separate time periods. Baseline clinical and pathological criteria were compiled, in addition to adjuvant treatments received, as well as number of lines of treatment in the metastatic setting. OS was compared across time cohorts for all patients and then between subtypes using Kaplan-Meier survival curves.

Results: A total of 3,953 patients met the inclusion criteria, consisting of 2,440 (61.7%) estrogen-receptor positive (ER+), 778 (19.7%) HER2 positive and 542 (13.7%) triple-negative breast cancer (TNBC) patients. One hundred and ninety-three patients (4.9%) were unable to be subtyped and were therefore excluded from the analysis . A total of 2,205 (90.4%) ER+ patients received at least 1 line of systemic therapy, with 80.0% receiving at least 1 line of hormonal therapy. The median time on hormonal treatment was 8.9 months (range 0.03 - 156.7) for first-line and 6.1 months (range 0.1 – 173.3) for second-line. In the HER2+ group, 665 (85.5%) patients received at least 1 line of treatment, with a median of 2 lines of treatment (range 1-16). Median duration of anti-HER2 treatment was 6.7 months (range 0.03 - 163.8) with a median of 1 line of anti-HER2 directed treatment (range 1-5). For TNBC patients, 357 (65.9%) received at least 1 line of treatment, with a median of 2 (range 1-10). No significant differences in OS were observed between the 3 time cohorts, with a median overall survival (mOS) of 1.63 years, 1.37 years and 1.57 years in cohorts 1-3, respectively (p=0.12).When comparing across subtypes, the ER+ group faired best with a mOS of 1.96 years (95% CI 1.8-2.1), consistent across time cohorts (p=0.72). This was followed by the HER2+ group with a mOS of 1.53 years (95% CI 1.3-1.7), also consistent across time cohorts (p=0.31). The TNBC group faired worst, with a mOS of 0.67 years (95% CI 0.6-0.8) over time (p=0.87).

Conclusions: Despite advances in systemic therapy since the early 2000s, no meaningful improvements in overall survival were observed over time, regardless of subtype. It remains to be seen if developments since 2013 will lead to gains in overall survival for MBC patients, at a real life, population-based level.

[1]Chia SK, Speers CH, D'yachkova Y, et al. Cancer 2007;110:973-979.

Citation Format: LeVasseur N, Fiorino L, Speers CH, Aparicio M, Lohrisch C, Chia SK. Prognosis and survival in metastatic breast cancer – Ten years in review, a population-based analysis [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-16-05.

Abstract P4-08-27: The 21-gene Recurrence® (RS) Score assay in estrogen receptor positive node negative breast cancer: Real-world chemotherapy usage and patient characteristics within the intermediate and high-risk RS category

Background:

The Oncotype Dx, a 21-gene recurrence score (RS) assay, has been validated as a prognostic tool in early-stage, hormone receptor-positive, HER2-negative breast cancer. A RS of ≥ 31 is predictive for chemotherapy benefit. However, it has not been clearly established whether more intensive chemotherapy regimens for these patients provide further benefit and whether higher RS stratifications (≥41) influence treatment decisions.

Methods:

From the prospective British Columbia (BC) Breast Cancer Outcomes Unit database, we identified patients with N0 disease who received Oncotype Dx testing from May 2010 to December 2016. Patients with previous or synchronous breast cancer, and patients treated with neoadjuvant chemotherapy were excluded. Groups were defined that had an Oncotype Dx RS of 31-40 and ≥ 41. Demographic characteristics and type of chemotherapy received were collected. Additional subgroups were defined for patients who had a RS of 21-25 and who were ≤ 50 years old and &gt; 50 years old.

Results:

We identified 1,202 patients who received Oncotype Dx testing over the time period studied, with 14.8% (n=178) having a RS of ≥ 31. Among these high-risk patients, the median age was 58 (range 34-79), 90% received hormonal therapy and 85% received chemotherapy. In this cohort, 46% received docetaxel and cyclophosphamide for 4 cycles and 28% received 3rd generation chemotherapy. The use of 3rd generation chemotherapy in patients with a RS of ≥ 41 was significantly higher than in patients with RS between 31-40 (39% vs 22%, p = 0.006). Among patients who had a RS of 21-25 and who were ≤ 50 years old (n = 49), 53% received chemotherapy. Of patients who had a RS of 21-25 and who were &gt; 50 years old (n = 127), 16% received chemotherapy.

Conclusions:

Among patients with a RS ≥ 31, decisions regarding chemotherapy usage were heterogeneous with docetaxel and cyclophosphamide for 4 cycles being the most commonly used regimen. However, in those with a RS ≥ 41, 3rd generation chemotherapy was preferred. Patients with a RS between 21-25 and who were ≤ 50 years old received more chemotherapy than patients who were &gt; 50 years old.

 RS 31-40 (n=116)RS ≥ 41 (n=62)RS ≥ 31 (n=178)Median age58.0 (range, 36-79)57.5 (range 34-78)58.0 (range 34-79)Pre-menopausal28.4%29.0%28.7%Hormonal therapy93.1%83.9%89.9%Chemotherapy86.2%82.3%84.8%DCx4 (1)54.3% (n=63/116) Median age 59.0 (range, 36 – 78)30.6% (n=19/62) Median age 64.0 (range, 42 – 78)46.1% (n=82/178) Median age 59.5 (range, 36 – 78)3rd generation chemo (2)21.6% (n=25/116) Median age 56.0 (range, 39 – 79)38.7% (n=24/62) Median age 52.0 (range, 34 – 76)27.5% (n=49/178) Median age 54.0 (range, 34 – 79)Other chemo10.3% (n=12/116) Median age 57.5 (range, 52 – 78)12.9% (n=8/62) Median age 64.0 (range, 42 – 72)11.2% (n=20/178) Median age 58.5 (range, 42 – 78)(1) Docetaxel and cyclophosphamide, 4 cycles (2) Anthracycline and Taxane containing regimens, 6 cycles or 8 cycles

Citation Format: Le D, Chia S, Simmons C, Speers C, Gondara L, Nichol A, Lohrisch C, Gelmon KA. The 21-gene Recurrence® (RS) Score assay in estrogen receptor positive node negative breast cancer: Real-world chemotherapy usage and patient characteristics within the intermediate and high-risk RS category [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-08-27.

Homologous Recombination Deficiency and Platinum-Based Therapy Outcomes in Advanced Breast Cancer

Purpose: Recent studies have identified mutation signatures of homologous recombination deficiency (HRD) in over 20% of breast cancers, as well as pancreatic, ovarian, and gastric cancers. There is an urgent need to understand the clinical implications of HRD signatures. Whereas BRCA1/2 mutations confer sensitivity to platinum-based chemotherapies, it is not yet clear whether mutation signatures can independently predict platinum response.Experimental Design: In this observational study, we sequenced tumor whole genomes (100× depth) and matched normals (60×) of 93 advanced-stage breast cancers (33 platinum-treated). We computed a published metric called HRDetect, independently trained to predict BRCA1/2 status, and assessed its capacity to predict outcomes on platinum-based chemotherapies. Clinical endpoints were overall survival (OS), total duration on platinum-based therapy (TDT), and radiographic evidence of clinical improvement (CI).Results: HRDetect predicted BRCA1/2 status with an area under the curve (AUC) of 0.94 and optimal threshold of 0.7. Elevated HRDetect was also significantly associated with CI on platinum-based therapy (AUC = 0.89; P = 0.006) with the same optimal threshold, even after adjusting for BRCA1/2 mutation status and treatment timing. HRDetect scores over 0.7 were associated with a 3-month extended median TDT (P = 0.0003) and 1.3-year extended median OS (P = 0.04).Conclusions: Our findings not only independently validate HRDetect, but also provide the first evidence of its association with platinum response in advanced breast cancer. We demonstrate that HRD mutation signatures may offer clinically relevant information independently of BRCA1/2 mutation status and hope this work will guide the development of clinical trials. Clin Cancer Res; 23(24); 7521-30. ©2017 AACR.

Long-term outcomes for neoadjuvant versus adjuvant chemotherapy in early breast cancer: meta-analysis of individual patient data from ten randomised trials

BACKGROUND

Neoadjuvant chemotherapy (NACT) for early breast cancer can make breast-conserving surgery more feasible and might be more likely to eradicate micrometastatic disease than might the same chemotherapy given after surgery. We investigated the long-term benefits and risks of NACT and the influence of tumour characteristics on outcome with a collaborative meta-analysis of individual patient data from relevant randomised trials.

METHODS

We obtained information about prerandomisation tumour characteristics, clinical tumour response, surgery, recurrence, and mortality for 4756 women in ten randomised trials in early breast cancer that began before 2005 and compared NACT with the same chemotherapy given postoperatively. Primary outcomes were tumour response, extent of local therapy, local and distant recurrence, breast cancer death, and overall mortality. Analyses by intention-to-treat used standard regression (for response and frequency of breast-conserving therapy) and log-rank methods (for recurrence and mortality).

FINDINGS

Patients entered the trials from 1983 to 2002 and median follow-up was 9 years (IQR 5-14), with the last follow-up in 2013. Most chemotherapy was anthracycline based (3838 [81%] of 4756 women). More than two thirds (1349 [69%] of 1947) of women allocated NACT had a complete or partial clinical response. Patients allocated NACT had an increased frequency of breast-conserving therapy (1504 [65%] of 2320 treated with NACT vs 1135 [49%] of 2318 treated with adjuvant chemotherapy). NACT was associated with more frequent local recurrence than was adjuvant chemotherapy: the 15 year local recurrence was 21·4% for NACT versus 15·9% for adjuvant chemotherapy (5·5% increase [95% CI 2·4-8·6]; rate ratio 1·37 [95% CI 1·17-1·61]; p=0·0001). No significant difference between NACT and adjuvant chemotherapy was noted for distant recurrence (15 year risk 38·2% for NACT vs 38·0% for adjuvant chemotherapy; rate ratio 1·02 [95% CI 0·92-1·14]; p=0·66), breast cancer mortality (34·4% vs 33·7%; 1·06 [0·95-1·18]; p=0·31), or death from any cause (40·9% vs 41·2%; 1·04 [0·94-1·15]; p=0·45).

INTERPRETATION

Tumours downsized by NACT might have higher local recurrence after breast-conserving therapy than might tumours of the same dimensions in women who have not received NACT. Strategies to mitigate the increased local recurrence after breast-conserving therapy in tumours downsized by NACT should be considered-eg, careful tumour localisation, detailed pathological assessment, and appropriate radiotherapy.

FUNDING

Cancer Research UK, British Heart Foundation, UK Medical Research Council, and UK Department of Health.

Willingness of breast cancer patients to undergo biopsy and breast cancer clinicians' practices around seeking biopsy at the time of breast cancer relapse

PURPOSE

The practice of seeking a biopsy to confirm a metastatic relapse of a prior breast cancer is individualized. Tumor samples have well-recognized importance in clinical and translational research, but also an increasing role in routine care. We sought to determine the attitudes of patients and breast cancer clinicians about biopsy at breast cancer relapses.

METHODS

Consenting breast cancer patients and clinicians completed questionnaires with scenarios of decreasing personal benefit and increasing discomfort or inconvenience associated with biopsy at relapse of a prior breast cancer. For each scenario, patients were asked whether they would, would not, or were unsure about agreeing to a biopsy. Clinicians provided information about their practice, research activities, and usual biopsy habits. They were asked to estimate how often patients would agree to a biopsy under each of the conditions presented to patient participants.

RESULTS

The majority of patients expressed a willingness to undergo a biopsy procedure of modest inconvenience and discomfort to establish an uncertain diagnosis, guide treatment, to participate in a trial, or for research purposes only. About 50% of patients indicated that they would undergo an invasive biopsy procedure requiring IV sedation or general anesthetic for purely altruistic reasons. In spite of being a largely academic group, clinician respondents underestimated patient willingness to have a biopsy in all scenarios, particularly when there was no attached personal benefit.

CONCLUSION

Breast cancer patients were very willing to undergo biopsy at breast cancer relapse for their routine care, clinical trials, or for research only. Clinicians act as the intermediary between patients and tumor tissue repositories, and clinician perceptions and practices should shift to match the altruistic attitudes of breast cancer patients.

Abstract 2473: Breast cancer whole genomes link homologous recombination deficiency (HRD) with therapeutic outcomes

Background: Homologous recombination deficiency (HRD) is common in cancer - germline BRCA1 & BRCA2 mutations account for 5-10% of breast cancers and confer 85% lifetime risk. HRD cancers exhibit genomic instability and sensitivity to platinum-based therapy and PARP inhibitors. While not all causes of HRD are known, recent sequencing efforts have revealed genome-wide somatic mutation signatures that characterize the HRD genomic instability phenotype, also known as “BRCA-ness”. This provides a promising new assay to predict sensitivity to platinum-based therapy. Here, we integrate two whole-genome sequencing metrics to assess their association with therapeutic outcomes in a breast cancer cohort.

Methods: Whole-genome sequencing of 47 breast cancer tumors (100x coverage) and matched normals (60x) was performed on an Illumina HiSeq. Alignment, assembly, SNV calling, and loss of heterozygosity (LOH) detection were performed with BWA, ABySS, Strelka, and APOLLOH respectively. SNV signatures were deciphered by non-negative matrix factorization with Monte Carlo resampling. An HRD score comprised of LOH, telomeric allelic imbalance (TAI), and large scale transition (LST) counts was computed. Clinical endpoints were obtained by retrospective review of treatment and imaging reports. Analysis is ongoing in an independent validation cohort of 62 sequenced cases.

Results: The HRD-linked SNV signature was significantly associated with radiographic clinical response (CR) to platinum-based therapy (p=0.015). Logistic regression demonstrated a 59% improved odds of CR to platinum-based therapy per 1000 somatic SNVs attributed to HRD (odds ratio 1.16-2.50). Tumors carried up to 10,246 such SNVs and all patients with CR were among the top quartile. The LOH-TAI-LST score was correlated with SNV signature (r=0.6, p=7×10-6) and associated with CR (p=0.025). Notably, elevated HRD signatures associated with CR were identified in tumors with wild-type BRCA1/BRCA2 or variants of unknown significance. Tumors with above median HRD signatures were associated with a 69-day longer time to treatment failure and an 18% daily decreased probability of treatment failure per 1000 HRD-attributed SNVs (hazard ratio 0.71-0.95, p = 0.007).

Discussion: We found that HRD mutation signatures are associated with clinical response and longer time to treatment failure with platinum-based therapy. While similar benefits were observed in patients with somatic bi-allelic loss of BRCA1/BRCA2, such cases are less common (8% of our cohort) compared to those with elevated HRD signature. Thus, mutation signature methods may identify patients who stand to benefit from platinum-based therapy missed by BRCA screening alone.

Citation Format: Eric Y. Zhao, Yaoqing Shen, Erin Pleasance, Katayoon Kasaian, Martin R. Jones, Carolyn Ch'ng, Caralyn Reisle, Peter Eirew, Karen Mungall, Nina Thiessen, Yussanne Ma, Alexandra Fok, Andrew J. Mungall, Yongjun Zhao, Richard Moore, Diego Villa, Tamara Shenkier, Caroline Lohrisch, Stephen Chia, Stephen Yip, Karen Gelmon, Howard Lim, Sophie Sun, Kasmintan A. Schrader, Sean Young, Aly Karsan, Robyn Roscoe, Janessa Laskin, Marco A. Marra, Steven J. Jones. Breast cancer whole genomes link homologous recombination deficiency (HRD) with therapeutic outcomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2473. doi:10.1158/1538-7445.AM2017-2473

Abstract P5-16-17: Population based long term outcomes of pathologic complete response after neoadjuvant chemotherapy in stage I-III breast cancer: The British Columbia experience

Background:

Neoadjuvant chemotherapy is a treatment option for breast cancer patients (pts) with locally advanced disease and for pts with operable breast cancer who desire breast conservation. Neoadjuvant therapy also allows for early evaluation of the effectiveness of systemic therapy. Pathologic complete response (pCR) has been shown in clinical trials to be associated with improved survival. The objective of this study was to determine if the outcomes demonstrated in clinical trials can be applied in the population based setting by comparing the outcomes of breast cancer pts who achieved pCR (no invasive disease in breast and nodes) vs. those that did not achieve a pCR.

Methods:

This is a retrospective cohort study of stage I-III invasive breast cancer pts treated with neoadjuvant chemotherapy from 2005 to 2010 in British Columbia. Cases were identified from the Breast Cancer Outcomes Unit database. Data was collected on demographics, tumor pathology, and type of treatment (chemotherapy, endocrine therapy, trastuzumab) and linked to standard clinical outcomes.

Results:

267 pts who met inclusion criteria were identified, of whom 5% had stage I, 33% Stage II and 59% Stage III breast cancer. Median follow up was 7.4 years. Overall 74 pts (28%) demonstrated a pCR and 193 pts did not. pCR pts had better 5-yr overall survival (OS) vs. non-pCR pts: 88% vs. 73% (HR 0.43, 95% CI 0.23-0.82, p=0.01). 5-yr disease free survival (DFS) was 84% in pCR pts vs. 70% in non-pCR pts (HR 0.45, 95% CI 0.24-0.83, p=0.01). Similarly, 5-yr breast cancer specific survival (BCSS) and distant disease free survival (DDFS) were significantly better in favor of the pCR cohort: HR 0.39 (95% CI 0.18-0.82, p=0.01) and HR 0.45 (95% CI 0.24-0.83, p=0.02) respectively. pCR pts were more likely to be HER2-positive and/or ER negative.

Conclusions:

Our population based results showed that early stage breast cancer pts who achieved pCR after neoadjuvant chemotherapy had better outcomes on all survival parameters compared to pts who did not achieve a pCR. This finding is consistent with results from neoadjuvant clinical trials and the FDA meta-analysis. These 'real world' results demonstrate that pCR can be used as a surrogate endpoint for survival outcomes even among non-trial pts.

Citation Format: Sun J, Gondara L, Diocee R, Speers C, Lohrisch C, Chia S. Population based long term outcomes of pathologic complete response after neoadjuvant chemotherapy in stage I-III breast cancer: The British Columbia experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-16-17.

A phase-I study of lapatinib in combination with foretinib, a c-MET, AXL and vascular endothelial growth factor receptor inhibitor, in human epidermal growth factor receptor 2 (HER-2)-positive metastatic breast cancer

BACKGROUND

The mechanisms of resistance to anti-human epidermal growth factor receptor 2 (HER 2) therapies are unclear but may include the tyrosine-protein kinase Met (c-Met), vascular endothelial growth factor (VEGF) and AXL pathways. Foretinib is an inhibitor of c-Met, VEGF receptor 2 (VEGFR-2), platelet-derived growth factor receptor beta (PDGFRB), AXL, Fms-like tyrosine kinase 3 (FLT3), angiopoiten receptor (TIE-2), RET and RON kinases. This phase Ib study sought to establish the associated toxicities, pharmacokinetics (PK) and recommended phase II doses (RP2D) of foretinib and lapatinib in a cohort of HER-2-positive patients with metastatic breast cancer (MBC).

METHODS

Women with HER-2 positive MBC, Performance status (PS 0-2), and no limit on number of prior chemotherapies or lines of anti-HER-2 therapies were enrolled. A 3 + 3 dose escalation design was utilized. Four dose levels were intended with starting doses of foretinib 30 mg and lapatinib 750 mg orally once a day (OD) on a 4-weekly cycle. Assessment of c-MET status from the primary archival tissue was performed.

RESULTS

We enrolled 19 patients, all evaluable for toxicity assessment and for response evaluation. Median age was 60 years (34-86 years), 95% were PS 0-1, 53% were estrogen receptor-positive and 95% had at least one prior anti-HER-2-based regimen. The fourth dose level was reached (foretinib 45 mg/lapatinib 1250 mg) with dose-limiting toxicities of grade-3 diarrhea and fatigue. There was only one grade-4 non-hematological toxicity across all dose levels. There were no PK interactions between the agents. A median of two cycles was delivered across the dose levels (range 1-20) with associated progression-free survival of 3.2 months (95% CI 1.61-4.34 months). By immunohistochemical assessment with a specified cutoff, none of the 17 samples tested were classified as positive for c-Met.

CONCLUSIONS

The RP2D of the combined foretinib and lapatinib is 45 mg and 1000 mg PO OD, respectively. Limited activity was seen with this combination in a predominantly unselected cohort of HER-2-positive patients with MBC.