Risk factors for the increasing incidence of pregnancy-associated cancer in Sweden - a population-based study

INTRODUCTION

The incidence of cancer during pregnancy and within first year post-delivery, ie pregnancy-associated cancer (PAC), is increasing in many countries, but little is known about risk factors for these trends. This study quantified incidence of PAC by trimesters and post-delivery periods, and assessed the role of maternal age, parity, immigrant status, education, smoking and body mass index for the risk and incidence trends of PAC.

MATERIAL AND METHODS

We used data from the national birth and cancer registers in Sweden during 1973-2017 to define a register-based cohort of women aged 15-44 years. Incidence rates of PAC during pregnancy and up to 1 year post-delivery were calculated per 100 000 deliveries per year. Poisson regression with multiple imputation estimated incidence rate ratios with 95% confidence intervals adjusted by year, age, previous parity, immigrant status, education, smoking and BMI during 1990-2017, when information on risk factors was available.

RESULTS

Among 4 557 284 deliveries, a total of 1274 (during pregnancy) and 3355 (within 1 year post-delivery) cases of PAC were diagnosed, with around 50 cases/year diagnosed during pregnancy and 110 cases/year during the first year post-delivery in the latest period 2015-2017. The most common cancer types during pregnancy were malignant melanoma, breast and cervical cancer, together accounting for 57% of cases during pregnancy and 53% during the first year post-delivery. The numbers of PAC were lower during pregnancy than during post-delivery for all tumor types with lowest numbers during first trimester. The PAC incidence rates increased over calendar time. High maternal age at diagnosis, smoking, nulliparity and non-immigrant background were associated with significantly higher risks of PAC. The increasing PAC incidence was in part explained by higher maternal age over time, but not by the other factors.

CONCLUSIONS

High maternal age is the strongest risk factor for PAC. We show for the first time that smoking, nulliparity and non-immigrant background are also contributing risk factors for PAC. However, only high maternal age contributed significantly to the increasing incidence. Further studies on other potential risk factors for PAC are warranted, since our results indicate that age on its own does not fully explain the increase.

Risk of obstetric and perinatal complications in women presenting with breast cancer during pregnancy and the first year postpartum in Sweden 1973-2017: A population-based matched study

INTRODUCTION

For women presenting with breast cancer during pregnancy, treatment guidelines were historically restricted to only surgical treatment. Over the past decades, chemotherapy administered during pregnancy has been gradually introduced. Although breast cancer treatments during ongoing pregnancy have been deemed safe, detailed information on potential obstetric risks is lacking. We aimed to assess the risk of adverse obstetric and perinatal outcomes of breast cancer in pregnancy and within 1 year postpartum and in relation to trimester at breast cancer diagnosis, tumor stage, and cancer treatment during pregnancy.

MATERIAL AND METHODS

Population-based matched study. Women diagnosed with breast cancer during pregnancy in 1973-2017 were identified in the Swedish Cancer Register and the Medical Birth Register, with additional information from the National Quality Register for Breast Cancer. Each birth with maternal breast cancer (n = 208 pregnant, n = 672 postpartum) was matched by age, calendar year, and birth order to 10 unexposed births from cancer-free women in the population (n = 2080 and n = 6720). Adjusted conditional logistic and multinomial regression models were used to estimate odds ratios and relative risk ratios, commonly denoted relative risks (RR) with 95% confidence intervals (CI), of adverse obstetric and perinatal outcomes.

RESULTS

Breast cancer during pregnancy was associated with higher risks of preterm birth, both planned (RR 67.1, 95% CI 33.2-135.6) and spontaneous preterm birth (RR 3.8, 95% CI 2.0-7.5), and low birthweight (<2500 g: RR 7.5, 95% CI 4.9-11.3). The associated risks were higher if the breast cancer was diagnosed in the second trimester, and of similar magnitude irrespective of stage and treatment groups. There was a higher risk of low birthweight for gestational age (<25th centile) if breast cancer was diagnosed in the first trimester (RR 2.8, 95% CI 1.1-7.3). Risks of other pregnancy complications were similar to those of unexposed women, as were risks of neonatal mortality and malformations. Postpartum breast cancer was only associated with bleeding during pregnancy (RR 1.6, 95% CI 1.0-2.8).

CONCLUSIONS

Preterm birth and related adverse outcomes were more common in women diagnosed with breast cancer during pregnancy. Reassuringly, breast cancer was not associated with other maternal pregnancy complications or adverse outcomes in children.

Worse histopathology and prognosis in women with breast cancer diagnosed during the second trimester of pregnancy

BACKGROUND

Evidence suggests that women with breast cancer diagnosed during pregnancy (PrBC) and within 2 years of delivery (PPBC) have similar survival compared to women diagnosed not near pregnancy if adjusted for stage and subtype. To investigate whether this is true for all subtypes and for both pregnancy and post-delivery periods, we examined clinicopathologic features and survival in women with breast cancer by trimesters and 6-month post-delivery intervals.

MATERIALS AND METHODS

Women diagnosed with invasive breast cancer during 1992-2018 at ages 18-44 years were identified in the Swedish Cancer Register, with information on childbirths from the Swedish Multi-Generation Register and clinical data from Breast Cancer Quality Registers. Each woman with PrBC or PPBC was matched 1 : 2 by age and year to comparators diagnosed with breast cancer not near pregnancy. Distributions of stage, grade, and surrogate subtypes were compared. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for breast cancer mortality were estimated using Cox regression.

RESULTS

We identified 1430 women with PrBC and PPBC (181 during pregnancy, 499 during the first and 750 during the second year after delivery). Compared to 2860 comparators, women with PrBC and PPBC in the first year after delivery had a significantly higher proportion of luminal human epidermal growth factor receptor 2 (HER2)-positive, HER2-positive and triple-negative tumours, and more advanced stage at diagnosis. After adjustment for age, year, parity, country of birth, hospital region, subtype, and stage, women diagnosed during the second trimester had a worse prognosis than matched comparators (HR 1.8, 95% CI: 1.0-3.2).

CONCLUSIONS

Women diagnosed during pregnancy or within the first year after delivery have a worse prognosis than women diagnosed not near pregnancy due to adverse tumour biology and advanced stage at diagnosis. A worse prognosis for women diagnosed during the second trimester remained after multivariable adjustment, possibly reflecting difficulties to provide optimal treatment during ongoing pregnancy.

Prognostic impact of HER2 biomarker levels in trastuzumab-treated early HER2-positive breast cancer

BACKGROUND

Overexpression of human epidermal growth factor receptor 2 (HER2) caused by HER2 gene amplification is a driver in breast cancer tumorigenesis. We aimed to investigate the prognostic significance of manual scoring and digital image analysis (DIA) algorithm assessment of HER2 copy numbers and HER2/CEP17 ratios, along with ERBB2 mRNA levels among early-stage HER2-positive breast cancer patients treated with trastuzumab.

METHODS

This retrospective study comprised 371 early HER2-positive breast cancer patients treated with adjuvant trastuzumab, with HER2 re-testing performed on whole tumor sections. Digitized tumor tissue slides were manually scored and assessed with uPath HER2 Dual ISH image analysis, breast algorithm. Targeted ERBB2 mRNA levels were assessed by the Xpert® Breast Cancer STRAT4 Assay. HER2 copy number and HER2/CEP17 ratio from in situ hybridization assessment, along with ERBB2 mRNA levels, were explored in relation to recurrence-free survival (RFS).

RESULTS

The analysis showed that patients with tumors with the highest and lowest manually counted HER2 copy number levels had worse RFS than those with intermediate levels (HR = 2.7, CI 1.4-5.3, p = 0.003 and HR = 2.1, CI 1.1-3.9, p = 0.03, respectively). A similar trend was observed for HER2/CEP17 ratio, and the DIA algorithm confirmed the results. Moreover, patients with tumors with the highest and the lowest values of ERBB2 mRNA had a significantly worse prognosis (HR = 2.7, CI 1.4-5.1, p = 0.003 and HR = 2.8, CI 1.4-5.5, p = 0.004, respectively) compared to those with intermediate levels.

CONCLUSIONS

Our findings suggest that the association between any of the three HER2 biomarkers and RFS was nonlinear. Patients with tumors with the highest levels of HER2 gene amplification or ERBB2 mRNA were associated with a worse prognosis than those with intermediate levels, which is of importance to investigate in future clinical trials studying HER2-targeted therapy.

Immune cell infiltrate in ductal carcinoma in situ and the risk of dying from breast cancer: case-control study

BACKGROUND

Studies identifying risk factors for death from breast cancer after ductal carcinoma in situ (DCIS) are rare. In this retrospective nested case-control study, clinicopathological factors in women treated for DCIS and who died from breast cancer were compared with those of patients with DCIS who were free from metastatic disease.

METHODS

The study included patients registered with DCIS without invasive carcinoma in Sweden between 1992 and 2012. This cohort was linked to the National Cause of Death Registry. Of 6964 women with DCIS, 96 were registered with breast cancer as cause of death (cases). For each case, up to four controls (318; women with DCIS, alive and without metastatic breast cancer at the time of death of the corresponding case) were selected randomly by incidence density sampling. Whole slides of tumour tissue were evaluated for DCIS grade, comedo necrosis, and intensity of periductal lymphocytic infiltrate. Composition of the immune cell infiltrate, expression of oestrogen receptor, progesterone receptor, human epidermal growth factor receptor 2, and proliferation marker Ki-67 were scored on tissue microarrays. Clinical information was obtained from medical records. Information on date, site, and histological characteristics of local and distant recurrences was obtained from medical records for both cases and controls.

RESULTS

Tumour tissue was analysed from 65 cases and 195 controls. Intense periductal lymphocytic infiltrate around DCIS was associated with an increased risk of later dying from breast cancer (OR 2.21. 95% c.i. 1.01 to 4.84). Tumours with more intense lymphocytic infiltrate had a lower T cell/B cell ratio. None of the other biomarkers correlated with increased risk of breast cancer death.

CONCLUSION

The immune response to DCIS may influence the risk of dying from breast cancer.

Impact of Primary Breast Surgery on Overall Survival of Patients With De Novo Metastatic Breast Cancer: A Systematic Review and Meta-Analysis

BACKGROUND

Breast surgery in cases of de novo metastatic breast cancer (MBC) is associated with improved outcomes in retrospective studies, although the results of randomized controlled trials (RCTs) are conflicting. We aimed to investigate whether surgery in this context prolongs patient survival.

METHODS

We performed a systematic review of the literature to identify RCTs comparing surgery of primary breast cancer to no surgery in patients with de novo MBC. Cochrane Library, Embase, Medline (OVID), and Web of Science were searched with latest update in July 2023, while conference proceedings were manually searched. Data concerning patient and tumor characteristics, as well as outcomes, were extracted. A meta-analysis with random effects models was performed considering heterogeneity between trials.

RESULTS

Overall, 3255 entries were identified and 5 RCTs fulfilled all inclusion criteria, which had enrolled 1381 patients. The overall estimation in the intention-to-treat population showed no benefit for patients who had surgical excision of the primary breast tumor (HR = 0.93; 95% CI, 0.76-1.14). No subgroups in terms of receptor status or patterns of metastasis seemed to benefit from surgery, except for younger/premenopausal patients (HR = 0.74, 95% CI, 0.58-0.94). Breast surgery was associated with improved local progression-free survival (HR = 0.37, 95% CI, 0.19-0.74).

CONCLUSION

Surgery of the primary tumor in patients with de novo MBC does not prolong survival, except possibly in younger/premenopausal patients. Breast surgery should be offered within the context of well-designed clinical trials examining the issue.

Treatment utilization and effectiveness of neoadjuvant chemotherapy comparing men and women diagnosed with breast cancer: a Swedish retrospective cohort study

PURPOSE

Evidence supporting the use of neoadjuvant chemotherapy (NAC) in early breast cancer is based on studies mainly including women, whereas the utilization and effectiveness of NAC in men is less studied. The present study aimed to investigate the utilization and effectiveness of NAC in men and women with early breast cancer.

METHODS

Eligible patients were identified through the Swedish National Breast Cancer Quality Register, that includes all newly diagnosed breast cancer cases in Sweden from 2008 and onwards. For the treatment utilization analysis, all patients with stage I-III between 2008 and 2020 were included (n = 82,888), whereas for the effectiveness analysis the cohort was restricted to patients receiving NAC (n = 6487). For both analyses, multivariate logistic regression models were applied to investigate potential sex disparities in NAC utilization and effectiveness, adjusted for patient- and tumor characteristics.

RESULTS

In the NAC utilization analysis, 487 men and 82,401 women with stage I-III were included. No statistically significant difference between sexes in terms of NAC utilization was observed (adjusted Odds Ratio (adjOR): 1.135; 95% Confidence Interval (CI) 0.606-2.128) with an overall utilization rate of 4.9% in men compared to 7.8% in women. Among the 24 men and 6463 women who received NAC, the pathologic complete response (pCR) rates were 16.7% and 21.2%, respectively (adjOR: 1.141; 95% CI 0.141-9.238).

CONCLUSION

The present study did not find any sex disparities in NAC utilization or effectiveness in terms of pCR. This supports the current recommendations of treating men with breast cancer with the same indications for NAC as women.

De novo metastatic breast cancer in men vs women: a Swedish population-based cohort study

Current evidence on de novo metastatic breast cancer is based on data from women. This Swedish population-based cohort study compared the incidence over time and prognosis of de novo metastatic breast cancer between sexes using data from the Swedish National Quality Register for Breast Cancer. Joinpoint regression analysis was used to compare incidence trends in all stages (104 733 women, 648 men) and multivariate Cox regression analysis to investigate potential sex disparities in de novo metastatic breast cancer prognosis (6005 women, 41 men). For both sexes, increased trends were evident for cancer stages I and II, with a stabilizing trend at the later years for women, while stage III incidence remained stable. An increased trend for de novo metastatic breast cancer in women, and to a lesser extent in men, was observed. No difference in de novo metastatic breast cancer overall survival between sexes was observed (hazard ratio = 1.24; 95% confidence interval = 0.85 to 1.81). The comparable features in terms of incidence and prognosis of de novo metastatic breast cancer between sexes imply similarities, supporting the adoption of common treatment strategies.

Risk-adjusted benchmarking of long-term overall survival in patients with HER2-positive early-stage Breast cancer: A Swedish retrospective cohort study

AIM

The main objective of the current study was to explore the value of risk-adjustment when comparing (i.e. benchmarking) long-term overall survival (OS) in breast cancer (BC) between Swedish regions. We performed risk-adjusted benchmarking of 5- and 10-year OS after HER2-positive early BC diagnosis between Sweden's two largest healthcare regions, constituting approximately a third of the total population in Sweden.

METHODS

All patients diagnosed with HER2-positive early-stage BC between 01-01-2009 and 31-12-2016 in healthcare regions Stockholm-Gotland and Skane were included in the study. Cox proportional hazards model was used for risk-adjustment. Unadjusted (i.e. crude) and adjusted 5- and 10-year OS was benchmarked between the two regions.

RESULTS

The crude 5-year OS was 90.3% in the Stockholm-Gotland region and 87.8% in the Skane region. The crude 10-year OS was 81.7% in the Stockholm-Gotland region and 77.3% in the Skane region. However, when adjusted for age, menopausal status and tumour biology, there was no significant OS disparity between the regions, neither at the 5-year nor 10-year follow-up.

CONCLUSION

This study showed that risk-adjustment is relevant when benchmarking OS in BC, even when comparing regions from the same country that share the same national treatment guidelines. This is, to our knowledge, the first published risk-adjusted benchmarking of OS in HER2-positive BC.

OptiBra study, a randomized controlled trial on optimal postoperative bra support after breast cancer surgery

AIM

This randomized controlled trial aimed to compare two different postoperative bras after breast cancer surgery and evaluate their impact on primary outcome pain.

METHOD

The study included 201 patients scheduled for primary surgery (breast conserving surgery with sentinel node biopsy or axillary clearance, mastectomy, or mastectomy with primary implant reconstruction with sentinel node biopsy or axillary clearance). Participants were randomized to either a soft bra or stable bra with compression. The patients were recommended to use the bra 24 h/day for 3 weeks, record daily pain (NRS), analgesic use and hours of bra use.

RESULTS

Follow up was completed by 184 patients. No significant differences between the arms were found considering pain score over time, neither day 1-14, nor after 3 weeks. Sixty-eight percent of all patients, regardless of randomization, reported pain during the first 14 days. After 3 weeks 46% still reported pain in the operated breast. Among these, patients randomized to the stable bra with compression reported significantly lower pain score than those randomized to the soft bra. Patients who used the stable bra with compression reported significantly higher levels of comfort, sense of security during activity, less difficulty moving the arm, as well as support and stability for the operated breast compared to those using the soft bra.

CONCLUSION

Using a stable bra with compression is the optimal evidence-based choice after breast cancer surgery to reduce remaining pain 3 weeks after surgery, increasing mobility, comfort, and sense of security.

TRIAL REGISTRATION NUMBER

NCT04059835 at www.

CLINICALTRIALS

gov.

Proteogenomics decodes the evolution of human ipsilateral breast cancer

Ipsilateral breast tumor recurrence (IBTR) is a clinically important event, where an isolated in-breast recurrence is a potentially curable event but associated with an increased risk of distant metastasis and breast cancer death. It remains unclear if IBTRs are associated with molecular changes that can be explored as a resource for precision medicine strategies. Here, we employed proteogenomics to analyze a cohort of 27 primary breast cancers and their matched IBTRs to define proteogenomic determinants of molecular tumor evolution. Our analyses revealed a relationship between hormonal receptors status and proliferation levels resulting in the gain of somatic mutations and copy number. This in turn re-programmed the transcriptome and proteome towards a highly replicating and genomically unstable IBTRs, possibly enhanced by APOBEC3B. In order to investigate the origins of IBTRs, a second analysis that included primaries with no recurrence pinpointed proliferation and immune infiltration as predictive of IBTR. In conclusion, our study shows that breast tumors evolve into different IBTRs depending on hormonal status and proliferation and that immune cell infiltration and Ki-67 are significantly elevated in primary tumors that develop IBTR. These results can serve as a starting point to explore markers to predict IBTR formation and stratify patients for adjuvant therapy.

Risk of coronary stenosis after adjuvant radiotherapy for breast cancer

Purpose

Adjuvant radiotherapy (RT) for breast cancer is associated with an increased risk of ischemic heart disease. We examined the risk of coronary artery stenosis in a large cohort of women with breast cancer receiving adjuvant RT.

Methods

A cohort of women diagnosed with breast cancer between 1992 and 2012 in three Swedish health care regions (n = 57,066) were linked to the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) to identify women receiving RT who subsequently underwent a percutaneous coronary intervention (PCI) due to coronary stenosis. Cox regression analyses were performed to examine risk of a coronary intervention and competing risk analyses were performed to calculate cumulative incidence.

Results

A total of 649 women with left-sided breast cancer and 494 women with right-sided breast cancer underwent a PCI. Women who received left-sided RT had a significantly higher risk of a PCI in the left anterior descending artery (LAD) compared to women who received right-sided RT, hazard ratio (HR) 1.44 (95% confidence interval [CI] 1.21–1.77, p < 0.001). For the proximal, mid, and distal LAD, the HRs were 1.60 (95% CI 1.22–2.10), 1.38 (95% CI 1.07–1.78), and 2.43 (95% CI 1.33–4.41), respectively. The cumulative incidence of coronary events at 25 years from breast cancer diagnosis were 7.0% in women receiving left-sided RT and 4.4% in women receiving right-sided RT.

Conclusion

Implementing and further developing techniques that lower cardiac doses is important in order to reduce the risk of long-term side effects of adjuvant RT for breast cancer.

Supplementary Information

The online version of this article (10.1007/s00066-022-01927-0) contains supplementary material, which is available to authorized users.

Abstract P1-02-03: Tumor-infiltrating lymphocytes but not HER2 copy number or ratio show prognostic value in trastuzumab-treated HER2-positive breast cancer

Background: Around 15% of all breast cancers are HER2+, a subtype that prior to HER2-targeted therapy was associated with a poor prognosis. With advances in treatment the survival has dramatically improved, and previous studies suggest that the level of HER2 copies are predictive of the effect of anti-HER2 therapies. However, some patients progress despite HER2-targeted therapy and routine HER2 testing is hampered by inaccuracy to discriminate patients with therapy-resistant disease. Furthermore, tumor-infiltrating lymphocytes (TILs) in the tumor stroma shows prognostic value not only in triple negative but also in HER2+ breast cancer. However, the clinical utility in the adjuvant setting for HER2+ disease needs further validation. The aim of this study was to investigate the prognostic significance of HER2/CEP17 ratio, HER2 copy numbers and TILs among early breast cancer patients treated with HER2-targeted therapy. Materials and methods: A retrospective study cohort comprising a total of 584 patients with HER2+ early breast cancer, all treated with the monoclonal antibody trastuzumab targeting HER2 during 2006-2014 in the Stockholm Region, Sweden, was identified and HER2 re-testing (silver in situ hybridization and immunohistochemistry (IHC)) was performed on 474 whole tissue sections prior to neoadjuvant (18.1%) or adjuvant therapy. Stromal TILs were manually assessed on all hematoxylin-eosin stained slides. Registry-based information on patient- and tumor characteristics including treatment were completed from medical records with a median follow-up of 8.0 years. Results: Among the 474 analyzed tumors, 11.4% were HER2 IHC score 2+ and 86.7% were 3+. In addition, 61.6% were ER+ and the median TIL score was 15%. The median HER2 copy number was 9.8 signals/cell and only 12.9% had &lt;6.0 average HER2 signals/cell and 2.5% had a HER2/CEP17 ratio &lt;2.0. Survival analysis showed no significant association between HER2 IHC score (recurrence: p=0.58; breast cancer specific death: p=0.69), HER2 signals (p=0.77; p=0.73), HER2/CEP17 ratio (p=0.73; p=0.85), ER status (p=0.55; p=0.11), PR status (p=0.97; p=0.46), Ki67 (p=0.14; p=0.77) or tumor grade (p=0.71; p=0.16) with risk of recurrence or breast cancer specific death. The hazard ratio (HR) for recurrence did not significantly differ by HER2 signals/cell (HR 1.12, CI 0.53-2.37, p=0.77) or ER status (HR 1.18, CI 0.68-2.05, p=0.55). Tumors with low TILs were independently associated with recurrence (cutoff &lt;40%: HR 4.5, CI 1.4-14.9, p=0.012) and breast cancer specific survival (cutoff &lt;30%: HR 3.5, CI 1.2-10.1, p=0.02). Among the 56 recurrences (11.8%), 37.5% had ER- primary tumors and 82.4% of the 34 HER2-analyzed recurrent tumors remained HER2+. Conclusions: This study demonstrates that routine clinicopathological data, including HER2 status, is insufficient to predict breast cancer recurrence among patients treated with HER2-targeted therapy. Neither HER2 levels, HER2/CEP17 ratio or ER status correlated to risk of recurrence. Importantly, TILs showed robust prognostic potential in trastuzumab-treated patients. Our results emphasize the need for detailed molecular analyses to understand the biology behind resistance to HER2-targeted therapy and to further tailor therapy for HER2+ breast cancer patients.

Citation Format: Stephanie Robertson, Caroline Rönnlund, Irma Fredriksson, Theodoros Foukakis, Johan Hartman. Tumor-infiltrating lymphocytes but not HER2 copy number or ratio show prognostic value in trastuzumab-treated HER2-positive breast cancer [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 P1-02-03.

The Natural History of Ductal Carcinoma In Situ of the Breast - An Overview

Ductal carcinoma in situ (DCIS) of the breast is a heterogenous disease and its natural history cannot be directly observed as surgical removal is part of the current standard of care. Studies of incompletely excised breast lesions that were considered benign after biopsy, but at review years later were recognized as DCIS, offers some insight to the natural history of DCIS. Summarizing these retrospective data; 14-53 % of the cases retrospectively diagnosed as DCIS progressed to invasive breast cancer (IBC) during follow-up. While observations from retrospective re-evaluation of biopsies and autopsies adds epidemiological input for understanding the natural history of DCIS, the most important results are still awaited from the ongoing prospective studies on active surveillance of DCIS. These studies with collected data on patient characteristics, life-style and environmental factors, as well as tumor and stromal metabolomics and genomics, will probably further elucidate the natural history of DCIS and how the disease should be treated in the future.

Local Recurrence after Treatment of Ductal Carcinoma In Situ: A Comprehensive Overview

Patients with DCIS have an excellent long-term prognosis with a 10-year breast cancer-specific survival around 98%. Treatment has the goal to prevent the development of an invasive breast cancer and to minimize the risk for a second breast cancer event, and published studies have shown a substantial decrease in invasive local recurrence rates over time. Approximately 50% of the local recurrences after BCS for a primary DCIS are invasive and 8.5% of them node-positive. Experiencing an ipsilateral invasive recurrence after a primary DCIS does significantly increase the risk of breast cancer death, while this is not seen after a DCIS recurrence. Radical surgery remains crucial to minimize the risk of local recurrence, and adjuvant radiotherapy reduces the risk of local recurrence by at least 50%. At recurrence, a repeat-BCS should be considered as it offers a good local control in properly selected patients and an overall and breast cancer-specific survival comparable to that seen after mastectomy.

Risk of primary lung cancer after adjuvant radiotherapy in breast cancer-a large population-based study

Adjuvant radiotherapy (RT) for breast cancer (BC) has been associated with an increased risk of later radiation-induced lung cancer (LC). We examined the risk of primary LC in a population-based cohort of 52300 women treated for BC during 1992 to 2012, and 253796 age-matched women without BC. Cumulative incidence of LC was calculated by the Kaplan-Meier method, and the risk of LC after BC treatment was estimated by Cox proportional hazards regression analyses. Women with BC receiving RT had a higher cumulative incidence of LC compared to women with BC not receiving RT and women without BC. This became apparent 5 years after RT and increased with longer follow-up. Women with BC receiving RT had a Hazard ratio of 1.59 (95% confidence interval 1.37-1.84) for LC compared to women without BC. RT techniques that lower the incidental lung doses, e.g breathing adaption techniques, may lower this risk.

In modern times, how important are breast cancer stage, grade and receptor subtype for survival: a population-based cohort study

Background

In breast cancer, immunohistochemistry (IHC) subtypes, together with grade and stage, are well-known independent predictors of breast cancer death. Given the immense changes in breast cancer treatment and survival over time, we used recent population-based data to test the combined influence of IHC subtypes, grade and stage on breast cancer death.

Methods

We identified 24,137 women with invasive breast cancer aged 20 to 74 between 2005 and 2015 in the database of the Cancer Registry of Norway. Kaplan-Meier curves, mortality rates and adjusted hazard ratios for breast cancer death were estimated by IHC subtypes, grade, tumour size and nodal status during 13 years of follow-up.

Results

Within all IHC subtypes, grade, tumour size and nodal status were independent predictors of breast cancer death. When combining all prognostic factors, the risk of death was 20- to 40-fold higher in the worst groups compared to the group with the smallest size, low grade and ER+PR+HER2− status. Among node-negative ER+HER2− tumours, larger size conferred a significantly increased breast cancer mortality. ER+PR−HER2− tumours of high grade and advanced stage showed particularly high breast cancer mortality similar to TNBC. When examining early versus late mortality, grade, size and nodal status explained most of the late (> 5 years) mortality among ER+ subtypes.

Conclusions

There is a wide range of risks of dying from breast cancer, also across small breast tumours of low/intermediate grade, and among node-negative tumours. Thus, even with modern breast cancer treatment, stage, grade and molecular subtype (reflected by IHC subtypes) matter for prognosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13058-021-01393-z.

Predictive role of HER2-status on the effectiveness of endocrine adjuvant treatment in postmenopausal breast cancer patients: a population-based cohort study

PURPOSE

There are conflicting results on the potential role of HER2-status on the efficacy of aromatase inhibitors (AIs) and tamoxifen (TAM) in patients with hormone receptor (HR)-positive breast cancer (BC). The purpose of this population-based cohort study was to investigate the potential benefit of AIs compared to TAM as adjuvant therapy in postmenopausal BC patients by HER2-status in the era of modern therapy with HER2-blockade.

METHODS

A population-based cohort study was performed including all postmenopausal women diagnosed with HR-positive BC without distant metastasis between 2007 and 2012 in three healthcare regions in Sweden. We analyzed the breast cancer-specific survival (BCSS) and overall survival (OS) in two distinct cohorts (HER2-negative, HER2-positive) based on the type of endocrine therapy (ET) used. A propensity score matching was performed separately in the HER2-negative and HER2-positive cohorts, respectively.

RESULTS

After propensity score matching, 4368 patients with HER2-negative and 214 patients with HER2-positive BC were available for analysis. In the HER2-negative cohort, an improved BCSS [Hazard Ratio (HR): 0.51; 95% confidence interval (CI): 0.34-0.77, p value < 0.001] and a trend toward improved OS (HR: 0.66; 95% CI: 0.41-1.08, p value = 0.093) in favor of AI-based therapy was observed. In the HER2-positive cohort, no statistically significant difference between AI-based ET and TAM was found in terms of either BCSS or OS, although the direction of HR was similar as in the HER2-negative cohort (HR for BCSS: 0.84; 95% CI: 0.14-5.04, p = 0.849; HR for OS: 0.62; 95% CI: 0.10-3.38, p = 0.345).

CONCLUSION

Our study results, based on propensity-matched cohorts, did not support any predictive value of HER2-status on endocrine therapy in postmenopausal BC patients. AI-based ET remains the treatment of choice for postmenopausal BC patients with HR-positive disease in the modern era of HER2-directed therapy irrespective of HER2-status.

Impact of chemotherapy, radiotherapy, and endocrine therapy on sick leave in women with early-stage breast cancer during a 5-year period: a population-based cohort study

Purpose

To examine the influence of type of oncological treatment on sick leave in women of working age with early-stage breast cancer.

Methods

We identified 8870 women aged 30–64 diagnosed with stage I–II breast cancer between 2005 and 2012 in the Breast Cancer Data Base Sweden. Associations between type of oncological treatment (radiotherapy, endocrine therapy, and chemotherapy) and sick leave were estimated by hazard ratios, probabilities, and length of sick leave using multi-state survival analysis.

Results

During the first 5 years after diagnosis, women aged 50–54 years at diagnosis receiving chemotherapy spent on average 182 (95% CI 151–218) additional days on sick leave compared with women not receiving chemotherapy, but with otherwise similar characteristics. Correspondingly, women initiating endocrine therapy spent 30 (95% CI 18–44) additional days on sick leave and women receiving post-mastectomy radiotherapy 53 (95% CI 37–69) additional days. At year five, the rate of sick leave was increased in women who had received chemotherapy (HR 1.19, 95% CI 1.11–1.28) or endocrine therapy (HR 1.15, 95% CI 1.05–1.26). Chemotherapy and endocrine therapy were associated with increased rates of sick leave due to depression or anxiety.

Conclusion

Our findings of increased long-term risks of sick leave after oncological treatment for breast cancer warrant attention from caregivers taking part in cancer rehabilitation. In light of the ongoing debate about overtreatment of early-stage breast cancer, our findings point to the importance of properly selecting patients for chemotherapy not only for the medical toxicity but also the possible impact on their livelihood.

Electronic supplementary material

The online version of this article (10.1007/s10549-020-05720-4) contains supplementary material, which is available to authorized users.

Mammography screening reduces rates of advanced and fatal breast cancers: Results in 549,091 women

BACKGROUND

It is of paramount importance to evaluate the impact of participation in organized mammography service screening independently from changes in breast cancer treatment. This can be done by measuring the incidence of fatal breast cancer, which is based on the date of diagnosis and not on the date of death.

METHODS

Among 549,091 women, covering approximately 30% of the Swedish screening-eligible population, the authors calculated the incidence rates of 2473 breast cancers that were fatal within 10 years after diagnosis and the incidence rates of 9737 advanced breast cancers. Data regarding each breast cancer diagnosis and the cause and date of death of each breast cancer case were gathered from national Swedish registries. Tumor characteristics were collected from regional cancer centers. Aggregated data concerning invitation and participation were provided by Sectra Medical Systems AB. Incidence rates were analyzed using Poisson regression.

RESULTS

Women who participated in mammography screening had a statistically significant 41% reduction in their risk of dying of breast cancer within 10 years (relative risk, 0.59; 95% CI, 0.51-0.68 [P < .001]) and a 25% reduction in the rate of advanced breast cancers (relative risk, 0.75; 95% CI, 0.66-0.84 [P < .001]).

CONCLUSIONS

Substantial reductions in the incidence rate of breast cancers that were fatal within 10 years after diagnosis and in the advanced breast cancer rate were found in this contemporaneous comparison of women participating versus those not participating in screening. These benefits appeared to be independent of recent changes in treatment regimens.

Early detection of breast cancer rectifies inequality of breast cancer outcomes

Objectives

To explain apparent differences among mammography screening services in Sweden using individual data on participation in screening and with breast cancer–specific survival as an outcome.

Methods

We analysed breast cancer survival data from the Swedish Cancer Register on breast cancer cases from nine Swedish counties diagnosed in women eligible for screening. Data were available on 38,278 breast cancers diagnosed and 4312 breast cancer deaths. Survival to death from breast cancer was estimated using the Kaplan–Meier estimate, for all cases in each county, and separately for cases of women participating and not participating in their last invitation to screening. Formal statistical comparisons of survival were made using proportional hazards regression.

Results

All counties showed a reduction in the hazard of breast cancer death with participation in screening, but the reductions for individual counties varied substantially, ranging from 51% (95% confidence interval 46–55%) to 81% (95% confidence interval 74–85%). Survival rates in nonparticipating women ranged from 53% (95% confidence interval 40–65%) to 74% (95% confidence interval 72–77%), while the corresponding survival in women participating in screening varied from 80% (95% confidence interval 77–84%) to 86% (95% confidence interval 83–88%), a considerably narrower range.

Conclusions

Differences among counties in the effect of screening on breast cancer outcomes were mainly due to variation in survival in women not participating in screening. Screening conferred similarly high survival rates in all counties. This indicates that the performance of screening services was similar across counties and that detection and treatment of breast cancer in early-stage reduces inequalities in breast cancer outcome.

Abstract P5-02-07: Distribution of biomarker evaluation scores among the pathology departments of Sweden: Comparison study of 35,066 breast cancer cases

Background/Aim: Correct assessments of prognostic and predictive markers (ER, PgR, HER2, histological grade) are essential in the choice of adjuvant therapy in primary breast cancer. Comparisons of department performances are necessary to ensure that daily diagnostic practice meets clinical requirements. Here we compared the distribution of biomarker evaluation scores among the pathology departments in Sweden.

Methods: All breast cancer cases diagnosed 2013 to 2017 in Sweden were identified in the National Quality Register for Breast Cancer. All cases with results on ER, PgR, HER2, Ki67 and histological grade tested on surgical resection specimens were selected. Only pathology departments with more than 450 diagnosed breast cancer cases in the given period of time were included in the study, resulting in 35,066 cases from 29 investigated departments across Sweden. All pathology departments follow the national guidelines of biomarker evaluation. The distribution of breast cancer phenotypes across the regions of Sweden is considered homogenous. We used Kruskal-Wallis test with Dunn’s post-hoc analysis, and χ2 tests to compare the departments resulting in totally 406 comparisons per marker. We applied Bonferroni correction in multiple comparisons. The trend of biomarkers score distribution among departments was investigated using joinpoint analysis.

Results: We found significant difference in biomarker evaluation scores among the pathology departments for all the investigated markers (p&lt;0.001 for all markers). Regarding hormone receptors, only 3 comparisons were significantly different for ER status, while 56 out of 406 comparisons were significantly different for PgR status (p&lt;0.05). The distribution of positive cases among the departments ranged from 85.2% to 91.6% for ER status and from 67.2% to 83.9% for PgR. Trend analysis showed that 21 departments were in the same trend for the distribution of hormone receptor positive cases (ER: 86.3%-89% PgR: 70%-77.1%, p&lt;0.001 for both markers. Regarding HER2 status, 23 comparisons were significantly different. The median percentage of HER2 positive cases were 11.7%. The distribution varied between 7.2% and 16.2% and the joinpoint analysis showed 4 trends among the departments as follows: 2 departments with 7.1% and 8.2%; 10 departments between 9.2%-10.9%; 12 departments between 11.5%-13.3% and 5 departments between 14%-16.2% (p=0.01). Considering Ki67, 175 comparisons were significantly different (p&lt;0.05). The distribution of Ki67 low cases ranged between 23.5%-67.4% showing 4 trends among the departments: 2 departments with 23.5% and 33.7%, 11 departments between 37.8%-48.2%, 14 departments between 49.1%-58.5 and 2 departments with 60.2% and 67.4% (p=0.008). We found 92 comparisons significantly different during the investigation of histological grade scores among the departments (p&lt;0.05). The distribution of Grade 3 cases varied between 17.4%-37.9% and the joinpoint analysis showed 4 trends among the departments as follows: 3 departments between 17.4% and 22.5%; 11 departments between 24.8%-30.5%; 11 departments between 30.9%-32.5% and 4 departments between 33.7%-37.9% (p&lt;0.001).

Conclusions: Variability in biomarker evaluation exists among Swedish pathology departments despite using the same guidelines, internal and external quality assurance for several years. The lowest variability was found for ER and HER2 testing, while histological grade and Ki67 assessment showed the highest variability among departments. The discrepancy was likely due to pre-analytical, analytical as well as scoring factors.

Citation Format: Balazs Acs, Irma Fredriksson, Ulla Wilking, Stephanie Robertson, Johan Hartman. Distribution of biomarker evaluation scores among the pathology departments of Sweden: Comparison study of 35,066 breast cancer cases [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-02-07.

Abstract P3-08-19: Biomarkers associated with dcis related breast cancer death

Introduction In primary ductal carcinoma in situ of the breast (DCIS) tumour biological features associated with risk of invasive recurrence and metastasis may already be present at the pre-invasive stage. The aim of this study was to investigate the correlation of biological markers in DCIS and the risk of subsequent breast cancer death. Patients and methods A nested case-control study was conducted in a population based cohort of women diagnosed with primary DCIS between 1992 and 2012. Women who later died from breast cancer were identified. Four controls per case were selected randomly by incidence density sampling from the same cohort. Tumour blocks were retrieved for histopathological reevaluation and immunohistochemical analysis (IHC) of Oestrogen Receptor (ER), Progesterone Receptor (PR), Human Epidermal Growth Receptor 2 (HER2) and Ki67 expression. Odds ratios (OR) for risk of breast cancer death with 95% CI was calculated using conditional logistic regression. Results From a cohort of 6964 women with primary DCIS, tumour specimens were available for 66 patients who died from breast cancer and these were compared to samples from 195 controls. DCIS with intense lymphocytic infiltration was associated with an increased risk of breast cancer related death in univariate analysis (OR 2.25; 95%CI 1.02-4.99). None of the biomarkers were individually related to increased risk. In multivariable analysis and stepwise adjusting for age, tumour size and treatment; PR negativity in combination with lymphocytic infiltration (OR 4.40; 95%CI 1.20-16.14), PR negativity, lymphocytic infiltration and presence of comedonecrosis (OR 5.48; 95%CI 1.71-17.57) and the combination of PR negativity, lymphocytic infiltration, comedonecrosis and HER2 positivity (OR 7.54; 95%CI 2.00-28.43) were all independently associated with increased risk of breast cancer related death. Conclusion In the present study, the combination of PR negativity and periductal lymphocytic infiltration was associated with risk of breast cancer related death after primary DCIS. Combining biomarker expressions in DCIS with features in the peritumoural stroma may be useful tools for prognostication.

Citation Format: Charlotta Wadsten, Johan Hartman, Irma Fredriksson, Hans Garmo, Fredrik Wärnberg, Malin Sund. Biomarkers associated with dcis related breast cancer death [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P3-08-19.

Bleeding risk in breast cancer patients during concomitant administration of warfarin and tamoxifen: A population-based nested case-control study

We aimed to investigate whether the concomitant use of tamoxifen with warfarin is associated with higher risk for bleeding among patients with early estrogen-receptor (ER)-positive breast in a population-based nested case-control study. We identified 1787 patients taking warfarin and 92 cases hospitalized for bleeding and found an adjusted odds ratio (OR) of 1.42 (95% confidence interval (CI): 0.84-2.40) for the risk of bleeding in patients treated with warfarin that initiated tamoxifen within the previous 30 days. As a result, we could not definitively rule out a potential association between tamoxifen use during warfarin and bleeding risk in patients with breast cancer.

Long-term risk of ischemic heart disease after adjuvant radiotherapy in breast cancer: results from a large population-based cohort

BACKGROUND

Adjuvant radiotherapy (RT) for breast cancer (BC) has been associated with an increased risk of ischemic heart disease (IHD). We examined the incidence of IHD in a large population-based cohort of women with BC.

METHODS

The Breast Cancer DataBase Sweden (BCBaSe) includes all women diagnosed with BC from 1992 to 2012 (n = 60,217) and age-matched women without a history of BC (n = 300,791) in three Swedish health care regions. Information on comorbidity, educational level, and incidence of IHD was obtained through linkage with population-based registries. The risk of IHD was estimated by Cox proportional hazard regression analyses and cumulative incidence by the Kaplan-Meier method.

RESULTS

Women with BC had a lower risk of IHD compared to women without BC with a hazard ratio (HR) of 0.91 (95% CI 0.88-0.95). When women with left-sided BC were compared to right-sided BC, an increased HR for IHD of 1.09 (95% CI 1.01-1.17) was seen. In women receiving RT, a HR of 1.18 (95% CI 1.06-1.31) was seen in left-sided compared to right-sided BC, and the HRs increased with more extensive lymph node involvement and with the addition of systemic therapy. The cumulative IHD incidence was increased in women receiving left-sided RT compared to right-sided RT, starting from the first years after RT and sustained with longer follow-up.

CONCLUSIONS

Women given RT for left-sided BC during 1992 to 2012 had an increased risk of IHD compared to women treated for right-sided BC. These women were treated in the era of three-dimensional conformal RT (3DCRT), and the results emphasize the importance of further developing and implementing RT techniques that lower the cardiac doses, without compromising the beneficial effects of RT.

Abstract P2-08-05: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Jaraj D, Ahlgren J, Arnesson L-G, Einbeigi Z, Höijer J, Klintman M, Malmström P, Vikhe Patil E, Sund M, Fredriksson I, Bergh J, Pettersson A. Withdrawn [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 P2-08-05.

Diagnostic pathways and management in women with pregnancy-associated breast cancer (PABC): no evidence of treatment delays following a first healthcare contact

Background

Women with pregnancy-associated breast cancer (PABC), i.e. diagnosed during or within 2 years of pregnancy, have a poor prognosis. We compared symptoms, diagnostics, treatments, and waiting times from first symptoms to treatment initiation in women diagnosed with PABC and non-PABC.

Materials and methods

Women diagnosed with PABC and non-PABC at ages 15–44 were identified in Swedish healthcare registers. Chart information was retrieved for 546 women (273 PABC cases and 273 age- and hospital-matched non-PABC controls) treated at 11 hospitals across Sweden between 1992 and 2009. Distributions of symptoms, diagnostics and treatments were compared. Median waiting times from initial symptoms to start of treatment, and time periods within, were estimated from Kaplan–Meier curves.

Results

Initial symptoms in women with PABC and non-PABC were similar. Women with PABC more often underwent biopsy and ultrasound than mammography at initial examination. Compared to non-PABC, rates of mastectomy and axillary clearance were higher in women with PABC, while endocrine treatment was less common. The time from symptoms to first healthcare contact was non-significantly longer in women diagnosed during or within 6 months of pregnancy. Waiting times from contact with healthcare to diagnosis and treatment were shorter or similar in women with PABC compared to women with non-PABC.

Conclusions

These findings do not support the notion that diagnostic and treatment delays following a first healthcare contact are more common in women diagnosed with breast cancer during or shortly after pregnancy. However, there was some evidence of delays in seeking healthcare among pregnant and lactating women.

Electronic supplementary material

The online version of this article (10.1007/s10549-018-05083-x) contains supplementary material, which is available to authorized users.

No association between low-dose aspirin use and breast cancer outcomes overall: a Swedish population-based study

Background

Results from previous studies indicate that use of low-dose aspirin may improve breast cancer prognosis. We evaluated aspirin use and breast cancer outcomes in relation to clinical characteristics as well as dose and duration of aspirin use.

Methods

We used information from the Regional Breast Cancer Quality-of-Care Registries in three Swedish regions to identify 21,414 women diagnosed with a first stage I–III breast cancer between 1 April 2006 and 31 December 2012. The cohort was further linked to nationwide registers to retrieve information about dispensing low-dose aspirin before and after breast cancer diagnosis, comorbidity and causes of death. In a separate analysis, we investigated time to breast cancer death among 621 women with stage IV disease at diagnosis. Associations were evaluated using a multivariable Cox proportional hazards model.

Results

Among women with stage I–III breast cancer, 2660 (12.4%) used low-dose aspirin shortly before breast cancer diagnosis and 4091 (19.1%) were users during follow-up. Women were followed for a median of 3.8 years after diagnosis. There was no association between aspirin use and breast cancer-specific death in multivariable analyses (use before diagnosis: hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.77–1.12; use after diagnosis: HR 1.00, 95% CI 0.74–1.37). Similarly, aspirin use was not associated with risk of first recurrence/metastases in a subgroup of stage I–III breast cancer patients (HR 0.97, 95% CI 0.86–1.10). However, in analyses stratified by stage, an inverse association between low-dose aspirin use after diagnosis and breast cancer death was found for women with stage I tumors (HR 0.53, 95% CI 0.29–0.96). Among women with stage IV disease at diagnosis, aspirin use was not associated with time to breast cancer death (HR 0.91, 95% CI 0.67–1.23).

Conclusion

In this large population-based cohort study there was no evidence that low-dose aspirin use before or after breast cancer diagnosis is associated with a reduced risk of adverse outcomes overall in breast cancer. However, a potential benefit was noted among women with stage I tumors, warranting further investigation.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1065-0) contains supplementary material, which is available to authorized users.

Identification and validation of single-sample breast cancer radiosensitivity gene expression predictors

BACKGROUND

Adjuvant radiotherapy is the standard of care after breast-conserving surgery for primary breast cancer, despite a majority of patients being over- or under-treated. In contrast to adjuvant endocrine therapy and chemotherapy, no diagnostic tests are in clinical use that can stratify patients for adjuvant radiotherapy. This study presents the development and validation of a targeted gene expression assay to predict the risk of ipsilateral breast tumor recurrence and response to adjuvant radiotherapy after breast-conserving surgery in primary breast cancer.

METHODS

Fresh-frozen primary tumors from 336 patients radically (clear margins) operated on with breast-conserving surgery with or without radiotherapy were collected. Patients were split into a discovery cohort (N = 172) and a validation cohort (N = 164). Genes predicting ipsilateral breast tumor recurrence in an Illumina HT12 v4 whole transcriptome analysis were combined with genes identified in the literature (248 genes in total) to develop a targeted radiosensitivity assay on the Nanostring nCounter platform. Single-sample predictors for ipsilateral breast tumor recurrence based on a k-top scoring pairs algorithm were trained, stratified for estrogen receptor (ER) status and radiotherapy. Two previously published profiles, the radiosensitivity signature of Speers et al., and the 10-gene signature of Eschrich et al., were also included in the targeted panel.

RESULTS

Derived single-sample predictors were prognostic for ipsilateral breast tumor recurrence in radiotherapy-treated ER+ patients (AUC 0.67, p = 0.01), ER+ patients without radiotherapy (AUC = 0.89, p = 0.02), and radiotherapy-treated ER- patients (AUC = 0.78, p < 0.001). Among ER+ patients, radiotherapy had an excellent effect on tumors classified as radiosensitive (p < 0.001), while radiotherapy had no effect on tumors classified as radioresistant (p = 0.36) and there was a high risk of ipsilateral breast tumor recurrence (55% at 10 years). Our single-sample predictors developed in ER+ tumors and the radiosensitivity signature correlated with proliferation, while single-sample predictors developed in ER- tumors correlated with immune response. The 10-gene signature negatively correlated with both proliferation and immune response.

CONCLUSIONS

Our targeted single-sample predictors were prognostic for ipsilateral breast tumor recurrence and have the potential to stratify patients for adjuvant radiotherapy. The correlation of models with biology may explain the different performance in subgroups of breast cancer.

Abstract P4-09-08: A targeted breast cancer radiosensitivity gene expression panel

Background: A majority of patients with early breast cancer is operated with breast conserving surgery (BCS) and adjuvant radiotherapy (RT) is administered to prevent ipsilateral breast tumor recurrence (IBTR), including a new ipsilateral cancer. The EBCTCG meta-analysis showed a majority of patients treated with surgery only to be recurrence free at 10 years, and more than 10% to suffer an IBTR despite RT, thus implying considerable over- and under treatment. A wide range of prognosticators, including multigene tests, are well established, but we lack predictive factors for RT, which is the aim in the present study.

Patients and methods: Fresh frozen tissue from 340 patients operated with BCS with or without RT and with or without IBTR was collected (without IBTR N=196, with IBTR n=144). Patients were stratified according to estrogen receptor (ER) status and RT, and divided into a training cohort (N=172) and a validation cohort (N=168). The training cohort was analyzed with whole transcriptome analysis (Illumina HT12 v4) and top discriminating genes for IBTR (N=155) were selected based on a random forest machine learning algorithm with recursive feature elimination and cross-validation. Further, genes described in the literature as associated with radioresistance were included in the panel to a total of 248 genes. A custom nCounter (Nanostring Technologies) gene expression panel was designed and both the training and validation cohorts were analyzed with the custom panel. Single-sample classifiers using a k-top scoring pairs algorithm were trained in the training cohort and validated in the validation cohort. Area under the curve (AUC) with a receiver operator characteristics (ROC) analysis were calculated and p-values were calculated with a log-rank test. All calculations were done using the R statistical environment.

Results: Our classifiers were prognostic for IBTR in the validation cohort among ER+ patients given RT (AUC 0.67, p=0.005), ER+ patients not given RT (AUC=0.89, p=0.015) and ER- patients given RT (AUC=0.78, p&lt;0.001), while the number of ER- patients not given RT was too small for subgroup analysis (N=4). We also created a sequential algorithm were a first classifier was applied to test the risk of IBTR without RT. If low, the tumor was classified as “surgery only”. If classified as high, a second classifier was applied to test the risk of recurrence when given RT. If the risk was predicted low after RT, the tumor was classified as “radiosensitive”. If high, the tumor was classified as “radioresistant”. Among ER+ patients in the validation cohort, the “radiosensitive” tumors had an excellent effect of RT (p&lt;0.001), the “radioresistant” had no effect of RT (p=0.4) and a very high risk of recurrence (55% at 10 years). The tumors predicted as “surgery only” had no effect of RT (p=0.4), and a lower risk of recurrence than the “radioresistant” patients (25% at 10 years).

Conclusions: Our targeted radiosensitivity gene expression panel could identify patients of high or low risk of LR, with or without RT. The most promising was however that it seems as the panel could be used as a predictive marker, i.e., finding patients that do, or do not, respond to RT. Further refinement and testing of the panel and models is ongoing.

Citation Format: Sjöström M, Staaf J, Edén P, Wärnberg F, Bergh J, Malmström P, Fernö M, Niméus E, Fredriksson I. A targeted breast cancer radiosensitivity gene expression panel [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-09-08.

Breast cancer in young women and prognosis: How important are proliferation markers?

AIM

Compared to middle-aged women, young women with breast cancer have a higher risk of systemic disease. We studied expression of proliferation markers in relation to age and subtype and their association with long-term prognosis.

METHODS

Distant disease-free survival (DDFS) was studied in 504 women aged <40 years and 383 women aged ≥40 years from a population-based cohort. Information on patient characteristics, treatment and follow-up was collected from medical records. Tissue microarrays were produced for analysis of oestrogen receptor, progesterone receptor (PR), Her2, Ki-67 and cyclins.

RESULTS

Young women with luminal tumours had significantly higher expression of Ki-67 and cyclins. Proliferation markers were prognostic only within this subtype. Ki-67 was a prognostic indicator only in young women with luminal PR+ tumours. The optimal cut-off for Ki-67 varied by age. High expression of cyclin E1 conferred a better DDFS in women aged <40 years with luminal PR- tumours (hazard ratio [HR] 0.47 [0.24-0.92]). Age <40 years was an independent risk factor of DDFS exclusively in women with luminal B PR+ tumours (HR 2.35 [1.22-4.50]). Young women with luminal B PR- tumours expressing low cyclin E1 had a six-fold risk of distant disease compared with luminal A (HR 6.21 [2.17-17.6]).

CONCLUSIONS

The higher expression of proliferation markers in young women does not have a strong impact on prognosis. Ki-67 is only prognostic in the subgroup of young women with luminal PR+ tumours. The only cyclin adding prognostic value beyond subtype is cyclin E1. Age is an independent prognostic factor only in women with luminal B PR+ tumours.

Risk of death from breast cancer after treatment for ductal carcinoma in situ

Background

Studies to date have failed to demonstrate any survival benefit from preventing local recurrence after treatment for ductal breast carcinoma in situ (DCIS). Patient- and tumour-related risk factors for death from breast cancer in women with a primary DCIS were analysed here in a large case–control study.

Methods

A nested case–control study was conducted in a population-based cohort of women with primary DCIS between 1992 and 2012. Women who later died from breast cancer were identified. Four controls per case were selected randomly by incidence density sampling. Medical records and pathology reports were retrieved. Conditional logistic regression was used to calculate odds ratios (ORs) and 95 per cent confidence intervals for risk of death from breast cancer.

Results

From a cohort of 6964 women, 96 who died from breast cancer were identified and these were compared with a group of 318 controls. Tumour size over 25 mm or multifocal DCIS (OR 2·55, 95 per cent c.i. 1·53 to 4·25), a positive or uncertain margin status (OR 3·91, 1·59 to 9·61) and detection outside the screening programme (OR 2·12, 1·16 to 3·86) increased the risk of death from breast cancer. The risks were not affected by age or type of treatment. In the multivariable analysis, tumour size (OR 1·95, 1·06 to 3·67) and margin status (OR 2·69, 1·15 to 7·11) remained significant.

Conclusion

In the present study, large tumour size and positive or uncertain margin status were associated with a higher risk of death from breast cancer after treatment for primary DCIS. More extensive treatment was not associated with lower risk, which may be due to confounding by indication, or indicate that some DCIS has an inherent potential for metastatic spread.

Estrogen Receptor β as a Therapeutic Target in Breast Cancer Stem Cells

Background

Breast cancer cells with tumor-initiating capabilities (BSCs) are considered to maintain tumor growth and govern metastasis. Hence, targeting BSCs will be crucial to achieve successful treatment of breast cancer.

Methods

We characterized mammospheres derived from more than 40 cancer patients and two breast cancer cell lines for the expression of estrogen receptors (ERs) and stem cell markers. Mammosphere formation and proliferation assays were performed on cells from 19 cancer patients and five healthy individuals after incubation with ER-subtype selective ligands. Transcriptional analysis was performed to identify pathways activated in ERβ-stimulated mammospheres and verified using in vitro experiments. Xenograft models (n = 4 or 5 per group) were used to study the role of ERs during tumorigenesis.

Results

We identified an absence of ERα but upregulation of ERβ in BSCs associated with phenotypic stem cell markers and responsible for the proliferative role of estrogens. Knockdown of ERβ caused a reduction of mammosphere formation in cell lines and in patient-derived cancer cells (40.7%, 26.8%, and 39.1%, respectively). Gene set enrichment analysis identified glycolysis-related pathways (false discovery rate < 0.001) upregulated in ERβ-activated mammospheres. We observed that tamoxifen or fulvestrant alone was insufficient to block proliferation of patient-derived BSCs while this could be accomplished by a selective inhibitor of ERβ (PHTPP; 53.7% in luminal and 45.5% in triple-negative breast cancers). Furthermore, PHTPP reduced tumor initiation in two patient-derived xenografts (75.9% and 59.1% reduction in tumor volume, respectively) and potentiated tamoxifen-mediated inhibition of tumor growth in MCF7 xenografts.

Conclusion

We identify ERβ as a mediator of estrogen action in BSCs and a novel target for endocrine therapy.

Abstract P3-17-03: DCIS and the risk of breast cancer death - A case control study

Introduction

The risk of breast cancer death after a primary ductal carcinoma in situ (DCIS) is less than 2 % after 10 years. Whereas in situ recurrences do not influence survival, a 17-fold elevated risk of breast cancer specific mortality has been shown for invasive recurrences. Adjuvant radiotherapy (RT) effectively reduces recurrences after breast conserving surgery (BCS) for DCIS, but no studies have been able to demonstrate a survival benefit from adjuvant RT treatment or from choosing mastectomy instead of BCS. Here patient and tumour related risk factors for breast cancer death in women with a pure primary DCIS were studied.

Patients and methods

Women registered with a primary DCIS, between 1992-2012 in three of Sweden´s health care regions with a population of approximately 5.2 million, were enrolled in a nested case-control study. Out of 6,964 women with DCIS, 96 patients who later died from breast cancer were identified. Four controls per case (n=318) were randomly selected by incidence density sampling. We retrieved medical records and pathology reports and calculated OR with 95% CIs for various variables using conditional logistic regression.

Results

Of the 96 cases, 10 patients developed distant metastasis without a known local recurrence. In 56 patients death was preceded by an invasive ipsilateral recurrence and in 3 patients by a recurrent ipsilateral DCIS. Seven patients had invasive breast events in both the ipsilateral and the contralateral breast. Seventeen patients had contralateral invasive breast cancer and 3 patients contralateral DCIS.

Multifocality and tumour size over 25mm (OR 2.6 (1.6 to 4.2)), positive or uncertain margin status (OR 2.8 (1.6 to 4.9)) and detection outside screening (OR 2.1 (1.2 to 3.9)) increased the risk of breast cancer death in univariate analysis, when adjusted for age and year of diagnosis. Suspicion of micro-invasion and nuclear grade 3 was associated with a nonsignificant increased risk, OR 1.8 (0.6 to 5.0) and 2.6 (0.9-6.5), respectively. The risk was not affected by age or treatment. Tumour size and margin status remained significant in the multivariable analysis, when adjusted for treatment and for contralateral breast cancer (OR 2.0 (1.2 to 3.7)).

Conclusion

In the present study, large tumours and positive or uncertain margin status were significant risk factors for later breast cancer death after a primary DCIS. More extensive treatment was not related to a lower risk. The significance of tumour biology and nuclear grade will be further examined and evaluated.

Citation Format: Wadsten C, Garmo H, Fredriksson I, Sund M, Wärnberg F. DCIS and the risk of breast cancer death - A case control study [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 P3-17-03.

[Worse prognosis for young women with breast cancer]

Breast cancer in young women is uncommon, but the second most frequent cause of death in this age group. Young women with breast cancer have a worse prognosis than middle-aged women, with a higher risk of local recurrence, distant disease and breast cancer death. This can partly be explained by diagnosis at a later stage, and a higher proportion of tumors with unfavourable characteristics. However, in women with tumors of the luminal B subtype, low age remained an independent prognostic factor of DDFS and LRFS after correction for stage, tumor characteristics and treatment. Treatment of young women with breast cancer requires special skills to deal with the age group-specific questions concerning heredity, sexuality, fertility, and pregnancy.

Loss in working years after a breast cancer diagnosis: A population-based study (Sweden)

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Background: More than half of all women with breast cancer are diagnosed during working age. We present a new measure of clinical and public health relevance to estimate the loss in working years after a breast cancer diagnosis. Methods: Women of working age diagnosed with breast cancer between 1997 and 2012 were identified in the Breast Cancer Data Base Sweden (N = 19,661), together with a breast cancer-free comparison cohort (N = 81,303). Women were followed until permanent exit from the labour market (defined as receipt of disability pension, old-age retirement or death) or censoring. Using flexible parametric survival modelling, the loss in working years was calculated as the difference in the remaining years in the work force between women with and women without breast cancer. Results: The loss in working years was most pronounced in women of younger ages and in women with advanced stage disease. Women aged 50 years at diagnosis with stage I disease lost on average 0.6 years (95% CI, 0.4-0.8) of their remaining working time; the corresponding estimates were 1.2 years (1.0-1.5) in stage II, 3.2 years (2.7-3.7) in stage III, and 8.8 years (7.9-9.8) in stage IV disease. Type of treatment was a clear determinant in women with early stage disease, with a higher loss in working years among women treated with axillary surgery, mastectomy and chemotherapy. Conclusions: Our measure provides a new perspective of the burden of breast cancer in women of working age. The modest loss in working years in women with early stage disease is reassuring, although the economic consequences on a population-level are likely to be high given the large number of women diagnosed with breast cancer every year.

Sequencing-based breast cancer diagnostics as an alternative to routine biomarkers

Sequencing-based breast cancer diagnostics have the potential to replace routine biomarkers and provide molecular characterization that enable personalized precision medicine. Here we investigate the concordance between sequencing-based and routine diagnostic biomarkers and to what extent tumor sequencing contributes clinically actionable information. We applied DNA- and RNA-sequencing to characterize tumors from 307 breast cancer patients with replication in up to 739 patients. We developed models to predict status of routine biomarkers (ER, HER2,Ki-67, histological grade) from sequencing data. Non-routine biomarkers, including mutations in BRCA1, BRCA2 and ERBB2(HER2), and additional clinically actionable somatic alterations were also investigated. Concordance with routine diagnostic biomarkers was high for ER status (AUC = 0.95;AUC(replication) = 0.97) and HER2 status (AUC = 0.97;AUC(replication) = 0.92). The transcriptomic grade model enabled classification of histological grade 1 and histological grade 3 tumors with high accuracy (AUC = 0.98;AUC(replication) = 0.94). Clinically actionable mutations in BRCA1, BRCA2 and ERBB2(HER2) were detected in 5.5% of patients, while 53% had genomic alterations matching ongoing or concluded breast cancer studies. Sequencing-based molecular profiling can be applied as an alternative to histopathology to determine ER and HER2 status, in addition to providing improved tumor grading and clinically actionable mutations and molecular subtypes. Our results suggest that sequencing-based breast cancer diagnostics in a near future can replace routine biomarkers.

Effect of selective serotonin reuptake inhibitors use on endocrine therapy adherence and breast cancer mortality: a population-based study

The purpose of the study was to investigate whether the concomitant use of selective serotonin reuptake inhibitors (SSRI) with tamoxifen influences the risk of death due to breast cancer, and we also investigated the association between SSRI use and adherence to oral endocrine therapy (ET). We analyzed data from BCBaSe Sweden, which is a database created by the data linkage of Registries from three different regions of Sweden. To investigate the association between ET adherence and SSRI use, we included all women who were diagnosed with non-distant metastatic ER-positive invasive breast cancer from July 2007 to July 2011 and had at least one dispensed prescription of oral tamoxifen or aromatase inhibitor. To investigate the role of concurrent administration of SSRI and tamoxifen on breast cancer prognosis, we performed a nested case–control study. In the adherence cohort, 9104 women were included in the analyses. Women who received SSRI, either before or after breast cancer diagnosis, were at higher risk for low adherence to ET. However, when the overlapping period between SSRI use and ET was >50 %, no excess risk for low adherence was observed. Non-adherence (<80 %) to ET was significantly associated with worse breast cancer survival (OR 4.07; 95 % CI 3.27–5.06). In the case–control study, 445 cases and 11125 controls were included. The concomitant administration of SSRI and tamoxifen did not influence breast cancer survival, neither in short-term (OR 1.41; 95 % CI 0.74–2.68) nor in long-term SSRI users (OR 0.85; 95 % CI 0.35–2.08). Concomitant SSRI and tamoxifen use does not seem to increase risk for death due to breast cancer. Given the positive association between continuing antidepressive pharmacotherapy for a longer period of time and adherence to ET, it is essential to capture and treat depression in breast cancer patients to secure adherence to ET.

Time trends in axilla management among early breast cancer patients: Persisting major variation in clinical practice across European centers

Background We examined time trends in axilla management among patients with early breast cancer in European clinical settings. Material and methods EUROCANPlatform partners, including population-based and cancer center-specific registries, provided routinely available clinical cancer registry data for a comparative study of axillary management trends among patients with first non-metastatic breast cancer who were not selected for neoadjuvant therapy during the last decade. We used an additional short questionnaire to compare clinical care patterns in 2014. Results Patients treated in cancer centers were younger than population-based registry populations. Tumor size and lymph node status distributions varied little between settings or over time. In 2003, sentinel lymph node biopsy (SLNB) use varied between 26% and 81% for pT1 tumors, and between 2% and 68% for pT2 tumors. By 2010, SLNB use increased to 79-96% and 49-92% for pT1 and pT2 tumors, respectively. Axillary lymph node dissection (ALND) use for pT1 tumors decreased from between 75% and 27% in 2003 to 47% and 12% in 2010, and from between 90% and 55% to 79% and 19% for pT2 tumors, respectively. In 2014, important differences in axillary management existed for patients with micrometastases only, and for patients fulfilling the ACOSOG Z0011 criteria for omitting ALND. Conclusion This study demonstrates persisting differences in important aspects of axillary management throughout the recent decade. The results highlight the need for international comparative patterns of care studies in oncology, which may help to identify areas where further studies and consensus building may be necessary.

Abstract P6-10-08: Pregnancy associated breast cancer (PABC); no evidence of patients' or doctors' delays

Background:

A small, but not negligible, proportion of breast cancers in young women are detected in association with childbearing. While pregnancy usually is a period of intense medical observation, signs and symptoms of a malignancy may be overlooked or misinterpreted as pregnancy-related, resulting in diagnostic and treatment delays. Also, a delayed diagnosis in pregnant women has been suggested as a reason for the more advanced disease and poorer outcomes in women with pregnancy-associated breast cancer.

Material and Methods:

For the purpose of the present study, pregnancy-associated breast cancer (PABC) was defined as an invasive breast tumor diagnosed during pregnancy and up to two years post-delivery (non-PABC cases were diagnosed outside this time window, or nulliparous). Based on a systematic review of medical records for women aged 15-44 years at diagnosis with PABC and non-PABC identified in Swedish health care registers, chart information was retrieved by trained nurses for a total of 570 women (285 PABC women and 285 age and hospital matched non-PABC women) treated at 11 hospitals across Sweden between 1992 and 2009. Median waiting times from initial signs or symptoms in days to start of treatment, and time periods within, were computed using the Kaplan-Meier method and compared using the logrank test for the Kaplan-Meier curves. Dates on first symptoms were available for 122 matched PABC/non-PABC pairs, in total 244 patients. Full dates to assess and compare times between first health care contact – diagnosis – start of treatment, were available for 246 PABC/non-PABC pairs, in total 492 women.

Objective:

To examine and compare lengths of several defined waiting times within the time period from initial symptoms to start of treatment in women diagnosed with PABC and non-PABC.

Results:

Patient delay-time between first symptom and first point of contact with health care provider.

Median time between first symptoms and first contact with health care was 36 days and 45 days for women with PABC and non-PABC, respectively (logrank test p-value 0.48).

Time between first health care contact and diagnosis

Median time between first contact and diagnosis was 7 days for both PABC and non-PABC women (logrank test p-value 0.16).

Time between diagnosis and start of treatment

The median waiting time from date of diagnosis to initiation of treatment was shorter in women with PABC (22 days) compared to non-PABC women (26 days) (logrank test p-value 0.14).

Time between first contact and start of treatment

The median delay of start of treatment from first contact with a health care provider was 34 days in PABC women and 37 days in non-PABC women. (logrank test p-value 0.14).

Conclusions:

Patients' delay and the time between first contact with health care and start of treatment was shorter in women with PABC compared to non-PABC. Taken together, the present results do not support the notion that diagnostic and treatment delays are more common in women diagnosed with breast cancer during or shortly after pregnancy.

Citation Format: Lambe M, Fredriksson I, Johansson ALV. Pregnancy associated breast cancer (PABC); no evidence of patients' or doctors' delays. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-10-08.