Survival analysis of patients with brain metastases at initial breast cancer diagnosis over the last decade.

PURPOSE: There have been significant advances in the treatment of metastatic breast cancer (BC) over the past years, and long-term outcomes after a diagnosis of brain metastases are lacking. We aimed to identify predictors of brain metastases at initial breast cancer diagnosis, describe overall survival (OS) in the past decade, and identify factors associated with OS after brain metastases diagnosis. METHODS: We evaluated patients with de novo stage IV BC using the Surveillance, Epidemiology and End Results database from 2010 to 2019. Multivariate logistic regression was conducted to assess predictors of brain metastases at initial breast cancer diagnosis. OS was estimated using the Kaplan-Meier method and log rank test was used to compare differences between groups. Cox regression was used to assess associations between several variables and OS. RESULTS: 1,939 patients with brain metastases at initial breast cancer diagnosis were included. Factors associated with this presentation were grade III/IV tumors, ductal histology, hormone receptor (HR)-negative/human epidermal growth factor receptor 2 (HER2)-positive subtype, and extracranial metastases. Patients with HR-positive/HER2-positive disease had the longest OS (median 18 months) and 12.2% were alive at 8 years. Factors associated with shorter OS included older age, lower income, triple-negative subtype, higher grade, and visceral metastases. CONCLUSION: Over the last decade, the median OS of patients with brain metastases at initial breast cancer diagnosis remained poor; however, a substantial minority survive 5 or more years, with rates higher in patients with HER2-positive tumors. In addition to tumor subtype, OS varied according to age, extracranial metastases, and sociodemographic factors.

Quality of Life in Male Breast Cancer: Prospective Study of the International Male Breast Cancer Program (EORTC10085/TBCRC029/BIG2-07/NABCG).

INTRODUCTION: Prospective data about quality of life (QoL) in men with breast cancer (BC) are lacking. A prospective registry (EORTC10085) of men with all BC stages, including a QoL correlative study, was performed as part of the International Male Breast Cancer Program. METHODS: Questionnaires at BC diagnosis included the EORTC QLQ-C30 and BR23 (BC specific module), adapted for men. High functioning and global health/QoL scores indicate high functioning levels/high QoL; high symptom-focused measures scores indicate high symptoms/problems levels. EORTC reference data for healthy men and women with BC were used for comparisons. RESULTS: Of 422 men consenting to participate, 363 were evaluable. Median age was 67 years, and median time between diagnosis and survey was 1.1 months. A total of 114 men (45%) had node-positive early disease, and 28 (8%) had advanced disease. Baseline mean global health status score was 73 (SD: 21), better than in female BC reference data (62, SD: 25). Common symptoms in male BC were fatigue (22, SD: 24), insomnia (21, SD: 28), and pain (16, SD: 23), for which women's mean scores indicated more burdensome symptoms at 33 (SD: 26), 30 (SD: 32), and 29 (SD: 29). Men's mean sexual activity score was 31 (SD: 26), with less sexual activity in older patients or advanced disease. CONCLUSIONS: QoL and symptom burden in male BC patients appears no worse (and possibly better) than that in female patients. Future analyses on impact of treatment on symptoms and QoL over time, may support tailoring of male BC management.

Clinical behavior of recurrent hormone receptor-positive breast cancer by adjuvant endocrine therapy within the Breast International Group 1-98 clinical trial.

BACKGROUND: Endocrine therapy resistance is a major cause of distant recurrence (DR) in hormone receptor-positive breast cancer. This study evaluated differences in survival after DR in patients treated with different adjuvant endocrine therapy regimens in the Breast International Group (BIG) 1-98 trial. METHODS: BIG 1-98 compared 5 years of adjuvant treatment among 4 arms: tamoxifen (T), letrozole (L), tamoxifen followed by letrozole (TL), and letrozole followed by tamoxifen (LT). After a median follow-up of 8.1 years, 911 of 8010 patients (T, 302; L, 285; TL, 170; and LT, 154) had DR as the site of first recurrence. Univariate and multivariate Cox analyses were performed to determine features associated with post-DR survival. RESULTS: The median follow-up time after DR was 59 months (interquartile range, 29-88 months). Among all patients with DR, 38.1% were 65 years old or older at enrollment, 61.9% had tumors larger than 2 cm, and 69.7% were node positive. Neoadjuvant or adjuvant chemotherapy was administered to 35.6% of the patients. There was no difference in post-DR survival by treatment arm (median survival, 20.8 months for T, 17.9 months for L, 17.3 months for TL, and 20.8 months for LT; P = .21). In multivariate analysis, older patients (hazard ratio [HR], 1.35; 95% confidence interval [CI], 1.15-1.59) and patients with tumors larger than 2 cm (HR, 1.19; 95% CI, 1.00-1.41), 4 or more positive nodes (HR, 1.31; 95% CI, 1.05-1.64), progesterone receptor (PR)-negative tumors (HR, 1.25; 95% CI, 1.02-1.52), or shorter disease-free survival (DFS) had significantly worse post-DR survival. CONCLUSIONS: Treatment with adjuvant T, L, or their sequences was not associated with differences in survival after DR. Significant differences in survival were observed by age, primary tumor size, nodal and PR status, and DFS, and this suggests that traditional baseline high-risk features remain prognostic in the metastatic setting.

Factors associated with late risks of breast cancer-specific mortality in the SEER registry.

PURPOSE: Most reports describing the risk of late relapse in breast cancer (BC) have been based on selected patients enrolled into clinical trials. We examined population-based long-term risks of BC-specific mortality (BCSM), the risks of BCSM conditional on having survived 5 years, and factors associated with late BCSM. METHODS: Using SEER, we identified women diagnosed with BC (T1-T2, N0-N2, M0) between 1990 and 2005 with known hormone receptor (HR) status. Kaplan-Meier analyses determined cumulative risks of BCSM. We performed Fine and Gray regression stratified by HR status. RESULTS: We included 202,080 patients (median follow-up of 14.17 years). Of all BC deaths, the proportion that occurred after 5 years was 65% for HR-positive vs 28% for HR-negative (p < 0.001) BC. In HR-positive BC, the cumulative risks of BCSM during years 5-20 were 9.9%, 21.9%, and 38% for N0, N1, and N2 disease. For HR-negative BC, the risks were 7.9%, 12.2%, and 19.9%, respectively. For T1a/b, N0, HR-positive BC, the risk of BCSM was 6 times lower than the risk of non-BCSM. In N2, HR-positive BC, the risk of BCSM was 43% higher than the risk of non-BCSM. In adjusted Fine and Gray models stratified by HR status, the risks of BCSM conditional on having survived 5 years for both HR-positive and HR-negative depended on T-N status, age, and year of diagnosis. In HR-positive, the risks also depended on race and grade. CONCLUSION: The risks of BCSM beyond 5 years, although different, remain important for both HR-positive and HR-negative BC. Strategies to prevent early and late recurrences are warranted.

Twenty-year risks of breast cancer-specific mortality for stage III breast cancer in the surveillance, epidemiology, and end results registry.

PURPOSE: We aimed to report the 20-year risk of breast cancer-specific mortality (BCSM), report the risk of BCSM conditional on having survived 5 years, and identify factors associated with late deaths in stage III breast cancer. METHODS: Using Surveillance, Epidemiology, and End Results data, we included women with stage III breast cancer diagnosed from 1990 to 2005. We excluded women with unknown hormone receptor (HR) status, women who did not undergo resection of the primary tumor or axillary nodes, or unknown cause of death. We estimated risks of BCSM using cumulative incidence function and used Fine and Gray regression to identify factors associated with late deaths. RESULTS: Final sample was 36,500 patients with 14 years of median follow-up. For each stage subgroup, the risk of BCSM at 20 years was significantly higher for HR-negative vs HR-positive tumors (IIIA: 49.8% vs 43.2%, P < 0.0001; IIIB: 60.9% vs 47.6%, P < 0.0001; IIIC: 68.7% vs 63.1%, P < 0.0001). Compared with the risks of non-BCSM, the risks of BCSM at 20 years were four times higher in stage IIIC HR-positive disease and seven times higher in stage IIIC HR-negative disease. Risks of BCSM conditional on having survived 5 years depended on tumor size, nodal status, race, and tumor grade for HR-positive disease and depended on tumor size, nodal status, and age for HR-negative disease. CONCLUSIONS: In stage III breast cancer, the risk of BCSM at 20 years is very high and remains important even beyond the first 5 years in both HR-positive and HR-negative disease. Late BCSM depends on traditional clinicopathologic factors.

Breast cancer subtype and intracranial recurrence patterns after brain-directed radiation for brain metastases.

PURPOSE: Brain metastases from breast cancer are frequently managed with brain-directed radiation but the impact of subtype on intracranial recurrence patterns after radiation has not been well-described. We investigated intracranial recurrence patterns of brain metastases from breast cancer after brain-directed radiation to facilitate subtype-specific management paradigms. METHODS: We retrospectively analyzed 349 patients with newly diagnosed brain metastases from breast cancer treated with brain-directed radiation at Brigham and Women's Hospital/Dana-Farber Cancer Institute between 2000 and 2015. Patients were stratified by subtype: hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-), HER2+ positive (HER2+), or triple-negative breast cancer (TNBC). A per-metastasis assessment was conducted. Time-to-event analyses were conducted using multivariable Cox regression. RESULTS: Of the 349 patients, 116 had HR+/HER2- subtype, 164 had HER2+ subtype, and 69 harbored TNBC. Relative to HR+/HER2- subtype, local recurrence was greater in HER2+ metastases (HR 3.20, 95% CI 1.78-5.75, p < 0.001), while patients with TNBC demonstrated higher rates of new brain metastases after initial treatment (HR 3.16, 95% CI 1.99-5.02, p < 0.001) and shorter time to salvage whole brain radiation (WBRT) (HR 3.79, 95% CI 1.36-10.56, p = 0.01) and salvage stereotactic radiation (HR 1.86, 95% CI 1.11-3.10, p = 0.02). CONCLUSIONS: We identified a strong association between breast cancer subtype and intracranial recurrence patterns after brain-directed radiation, particularly local progression for HER2+ and distant progression for TNBC patients. If validated, the poorer local control in HER2+ brain metastases may support evaluation of novel local therapy-based approaches, while the increased distant recurrence in TNBC suggests the need for improved systemic therapy and earlier utilization of WBRT.

Survival Analysis of Male Patients with Brain Metastases at Initial Breast Cancer Diagnosis over the Last Decade.

Breast cancer in men represents approximately 1% of all breast cancer diagnoses. Among all patients with breast cancer, approximately 30% will develop brain metastases. Over the past decade, there have been multiple advances in the treatment of metastatic breast cancer; however, long-term outcomes of this presentation in male patients are lacking. We evaluated male patients with de novo stage IV breast cancer using the Surveillance, Epidemiology and End Results (SEER) database from 2010 to 2019. Overall survival (OS) was estimated using the Kaplan-Meier method and differences between groups were compared using log rank tests. In total, 22 male patients with brain metastases at initial breast cancer diagnosis were included. Patients with HR-positive/HER2-negative tumors had the longest OS (median 13 months). Factors associated with shorter overall survival were advanced age, unmarried marital status, lower household income, and grade III disease, among others. Brain metastases remains an unmet medical need for patients with breast cancer; the development of new drugs may provide an improvement in overall survival for male patients in the future.

Mortality Risks Over 20 Years in Men With Stage I to III Hormone Receptor-Positive Breast Cancer.

Importance: In women with hormone receptor-positive (HR+) breast cancer, the risk of distant recurrence and death persists for at least 20 years from diagnosis. The risk of late mortality in men with HR+ breast cancer has not been reported. Objective: To report 20-year risks of breast cancer-specific mortality (BCSM) and non-BCSM in men with stage I to III HR+ breast cancer and identify factors associated with late BCSM. Design, Setting, and Participants: An observational cohort study was conducted of men diagnosed with HR+ breast cancer from 1990 to 2008, using population-based data from the Surveillance, Epidemiology, and End Results program. Men diagnosed with stage I to III HR+ breast cancer were included in the analysis. Cumulative incidence function was used to estimate the outcomes of baseline clinicopathologic variables regarding cumulative risk of BCSM and non-BCSM since diagnosis. Smoothed hazard estimates over time were plotted for BCSM. Fine and Gray multivariable regression evaluated the association of preselected variables with BCSM, conditional on having survived 5 years. Main Outcome Measure: BCSM. Results: A total of 2836 men with stage I to III HR+ breast cancer were included, with a median follow-up of 15.41 (IQR, 12.08-18.67) years. Median age at diagnosis was 67 (IQR, 57-76) years. The cumulative 20-year risk of BCSM was 12.4% for stage I, 26.2% for stage II, and 46.0% for stage III. Smoothed annual hazard estimates for BCSM revealed an increase in late hazard rates with each incremental node category, reaching a bimodal distribution in N3 and stage III, with each having peaks in hazard rates at 4 and 11 years. Among patients who survived 5 years from diagnosis, the adjusted BCSM risk was higher for those younger than 50 years vs older than 64 years, those with grade II or III/IV vs grade I tumors, and stage II or III vs stage I disease. Conclusions and Relevance: The findings of this study suggest that, in men with stage I to III HR+ breast cancer, the risk of BCSM persists for at least 20 years and depends on traditional clinicopathologic factors, such as age, tumor stage, and tumor grade. Among men with higher stages of disease, the kinetics of the BCSM risk appear different from the risk that has been reported in women.

Prognosis and treatment outcomes for patients with stage IA triple-negative breast cancer.

To evaluate the role of chemotherapy in stage IA triple-negative breast cancer, we conducted a retrospective population-based study including 8601 patients. The use of chemotherapy significantly increased from 2010 to 2019 in patients with T1b and T1c tumors (p = 0.001 and p < 0.001, respectively). Receipt of chemotherapy was associated with improved breast cancer-specific survival (BCSS, adjusted hazard ratio = 0.70; p = 0.006), particularly in patients with T1c tumors (5-year BCSS 94.5% vs. 91.2%).

Subcutaneous vs Intravenous Trastuzumab/Pertuzumab: A Time and Motion Substudy of a Phase II Trial of Adjuvant Trastuzumab/Pertuzumab for Stage I HER2+ Breast Cancer (ADEPT trial).

PURPOSE: The time required for in-clinic drug administration can substantially affect breast cancer patients' quality of life. Subcutaneous (SC) drug administration, as opposed to intravenous (IV), may reduce this time commitment. This study sought to estimate the difference in time burden between IV and SC administration of trastuzumab and pertuzumab (HP). METHODS: We prospectively enrolled a subcohort of patients participating in the ADEPT trial (ClinicalTrials.gov identifier: NCT04569747, investigating adjuvant HP plus endocrine therapy for stage I human epidermal growth factor receptor 2-positive breast cancer) to this single-arm crossover time and motion substudy. Patients received two cycles of IV HP followed by two cycles of SC HP. During each cycle, time points in drug preparation and administration were captured. The primary end point was total patient time in the treatment chair. Additional end points included total patient treatment experience time and total pharmacy workflow time. A sample size of 22 patients was estimated to provide 90.7% power with two-sided alpha .05 to detect a difference of 70 minutes in the primary end point by treatment arm (IV v SC). RESULTS: Twenty-two patients were enrolled. The mean total patient time in the treatment chair was 61.8 minutes shorter with SC versus IV HP (22.5 v 84.3 minutes; P < .0001). The mean total patient treatment experience time (incorporating time spent waiting for treatment initiation and time spent in the treatment chair) was 81.8 minutes shorter for SC administration (96 v 177.8 minutes; P < .0001). The pharmacy workflow time was 78.2 minutes shorter for SC versus IV formulation (41 v 119.2 minutes; P < .0001). CONCLUSION: SC administration of HP shortened patient time burden by approximately 1 hour. SC drug administration can facilitate faster workflows for health care professionals and improve patients' breast cancer treatment experience.

Survival in male breast cancer over the past 3 decades.

BACKGROUND: Breast cancer mortality in women has declined statistically significantly over the past several years. In men, it is unclear whether survival has changed over time. We evaluated changes in breast cancer-specific survival (BCSS) and overall survival (OS) in male breast cancer over the past 3 decades. METHODS: We evaluated men diagnosed with breast cancer between 1988 and 2017, reported in the Surveillance, Epidemiology, and End Results registry. Patients were categorized into 3 groups by year of diagnosis: 1988-1997, 1998-2007, and 2008-2017. BCSS and OS were estimated by Kaplan-Meier, and differences between groups were compared by log-rank test. Multivariable Cox regression evaluated the independent association of year of diagnosis with BCSS and OS. All tests were 2-sided. RESULTS: We included 8481 men. Overall, BCSS at 5 years was 83.69%, 83.78%, and 84.41% in groups 1988-1997, 1998-2007, and 2008-2017, respectively (P = .86). There was no statistically significant difference in BCSS between the 3 groups within each stage of disease. Among all patients, OS at 5 years was 64.61%, 67.31%, and 69.05% in groups 1988-1997, 1998-2007, and 2008-2017, respectively (P = .01). In adjusted Cox models, each additional year of diagnosis had no statistically significant association with BCSS (hazard ratio = 1.00, 95% confidence interval = 0.99 to 1.01, P = .75), but there was statistically significant improvement in OS (hazard ratio = 0.99, 95% CI = 0.98 to 0.99, P = .009). CONCLUSIONS: Over the past 3 decades, there has been no statistically significant improvement in BCSS in male breast cancer. Changes in OS over time are consistent with increasing life expectancy. Efforts to improve BCSS in male breast cancer are warranted.

Estimating mortality in women with triple-negative breast cancer: The 'ESTIMATE triple-negative' tool.

PURPOSE: Triple-negative breast cancer (TNBC) is associated with a high risk of breast cancer-specific mortality (BCSM). Estimating the risk of BCSM and non-BCSM in TNBC would aid clinical decision-making. We developed the tool 'ESTIMATE-TN', to assess BCSM, non-BCSM, and all-cause mortality in non-metastatic TNBC. METHODS: Using Surveillance, Epidemiology, and End Results (SEER), we created an interactive tool that provides a nonparametric estimate of the cumulative risk of BCSM and non-BCSM between years 0 and 7 from diagnosis, accounting for baseline clinical and pathologic variables, using Gray's subdistribution method. RESULTS: We included 37,293 women with TNBC diagnosed during 2010-2017. Most patients were White (71.9%) and aged 50-69 years (51.3%). Most tumour characteristics were high-grade (78.6%), T2 (42.4%), and N0 (69.5%). ESTIMATE-TN allows to input patient and tumour characteristics, and the preferred timeframe. For example, patients aged 50-59 years with a new diagnosis of T2, N1, high-grade TNBC have a risk of BCSM at 7 years of 30.8% (95% confidence interval [CI]: 26.3-35.4%) and a risk of non-BCSM over the same period of 2.8% (95% CI: 1.3-4.3%). After 3 years from initial diagnosis, the residual cumulative risks of BCSM and non-BCSM at 7 years are 17.4% (95% CI: 12.6-22.2%) and 1.1% (95% CI: 0-2.5%), respectively. CONCLUSIONS: ESTIMATE-TN is an interactive tool for TNBC that can be used to integrate population-based risks of BCSM and non-BCSM based on patient and tumour characteristics, facilitating our understanding of competing risks of death, which can aid clinical decision-making.

Estimating long-term mortality in women with hormone receptor-positive breast cancer: The 'ESTIMATE' tool.

PURPOSE: The risk of breast cancer-specific mortality (BCSM) persists for at least 20 years from diagnosis. Estimating the risk of BCSM over this extended period along with competing risks of death would aid clinical decision-making. We aimed to develop an interactive tool called 'ESTIMATE', to explore the Surveillance, Epidemiology, and End Results (SEER) registry to quantify residual risks of BCSM, non-BCSM and all-cause mortality in non-metastatic, hormone receptor (HR)-positive breast cancer patient subgroups at any given time after diagnosis, up to 20 years. METHODS: Using SEER data, we included 264,237 women with invasive, non-metastatic, HR-positive breast cancer diagnosed from 1990 to 2006. We developed a tool that provides a nonparametric estimate of the residual cumulative risk of BCSM and non-BCSM by year 20 after any specified time from initial diagnosis, among patients defined by baseline clinical and pathologic variables, using Gray's subdistribution method. RESULTS: ESTIMATE allows the user to input patient and tumour characteristics and the preferred timeframe. For example, patients in the age group of 40-49 diagnosed with T1cN1, grade II breast cancer who survived 7 years, have a 14% (95% confidence interval [CI]: 11.9%-16.1%) residual cumulative risk of BCSM in the next 13 years, and a 6.4% (95% CI: 4.7%-8.1%) residual cumulative risk of non-BCSM over the same period. CONCLUSIONS: ESTIMATE provides population-based risks of BCSM, non-BCSM and all-cause mortality through 20 years after diagnosis of HR-positive breast cancer, based on patient and tumour characteristics. ESTIMATE can inform discussions about prognosis, a balance between competing risks and aid clinical decision-making.

Overall Survival of Men and Women With Breast Cancer According to Tumor Subtype: A Population-based Study.

OBJECTIVES: To analyze differences in overall survival (OS) between male breast cancer (MBC) and female breast cancer (FBC) according to tumor subtype compared with other factors. MATERIALS AND METHODS: We evaluated men and women with breast cancer between 2010 and 2013 with known hormone receptor (HR) status and human epidermal growth factor receptor 2 (HER2) status reported to the National Cancer Institute's Surveillance, Epidemiology, and End Results program. Patient characteristics were compared between groups. Univariate and multivariate analyses were performed to determine the effect of each variable on OS. Breast cancer-specific survival was a secondary endpoint. RESULTS: We included 1187 MBC and 166,054 FBC. Median follow-up was 21 months (range, 1 to 48) for both groups. OS at 3 years for MBC and FBC was 85.6% and 90.4%, respectively (P=0.0002). MBC were more ductal, had higher grade, presented with more advanced stage and were often HR+/HER2- (each P<0.0001). MBC had worse OS than FBC in HR+/HER2- (Hazard ratio [HaR], 1.5; P=0.0005), HR+/HER2+ (HaR, 2.8; P<0.0001) and triple negative (HaR, 4.3; P<0.0001) (Pinteraction<0.02). MBC had significantly worse OS than FBC in stages I and II, but similar OS in stages III and IV (Pinteraction<0.01). In multivariate analysis, HR+/HER2+ was the only subtype with significant differences in OS between MBC and FBC (HaR, 2.0; P=0.002). CONCLUSIONS: OS was significantly different in both groups. Men had worse OS in early stages while similar OS in stages III and IV. There were significant differences in OS according to tumor subtype; compared with women, men with HR+/HER2+ tumors had twice the risk of death.

Treatment Patterns and Survival of Elderly Patients With Breast Cancer Brain Metastases.

OBJECTIVES: The main objective of this study was to analyze treatment patterns of elderly patients with breast cancer brain metastases (BCBM), evaluate characteristics associated with treatment selection, and to analyze trends in overall survival (OS) over time. MATERIALS AND METHODS: We included women with BCBM reported to the Surveillance, Epidemiology, and End Results Medicare Program from 1992 to 2012. Treatments were recorded from Medicare claims from the date of brain metastases diagnosis until 60 days after. Treatments included resection, radiation, and chemotherapy. Cochran-Armitage tests were used for analysis of treatment patterns. Multinomial logistic regression was applied to determine factors associated with treatment selection. Cox regression modelled OS trends within each treatment modality across time. RESULTS: Among 5969 patients included, treatment rates increased from 50% in 1992 to 64.1% in 2012 (P<0.01). Therapy combining radiation, resection, and/or chemotherapy also increased from 8.8% to 18% over the same period (P<0.01). Combined therapy was significantly more likely among patients with extracranial metastases, those with estrogen-negative tumors, younger age at diagnosis, no comorbidities and more recently diagnosed brain metastases. OS improved over time for patients who received a combination of ≥2 treatments (hazard ratio, 0.89 per every 5 more recent diagnosis years; P<0.05). Older patients, those with extracranial metastases, or estrogen/progesterone-negative tumors showed significantly shorter OS. CONCLUSIONS: We observed substantial changes in treatment patterns and OS over time in patients with BCBM. We identified several factors associated with specific treatment use. Patients who underwent a combination of ≥2 treatments experienced a significant improvement in OS over time.

Prognostic Significance of Tumor Subtypes in Women With Breast Cancer According to Stage: A Population-based Study.

OBJECTIVES: The contribution of tumor subtypes (TS) in each stage of breast cancer with the use of contemporary therapies is unclear. The aim of this study was to analyze differences in overall survival (OS) by TS according to stage compared with other factors. MATERIALS AND METHODS: We evaluated women with breast cancer diagnosed between 2010 and 2013 with known estrogen receptor and progesterone receptor (together hormone receptor [HR]) status and human epidermal growth factor receptor 2 (HER2) status reported to the SEER program. Patient characteristics were compared between TS. Univariate and multivariate analyses were performed to determine the effect of each variable on OS. Breast cancer-specific survival was a secondary endpoint. RESULTS: We included 166,054 patients. TS distribution was: 72.5% HR-positive/HER2-negative, 10.8% HR-positive/HER2-positive, 4.8% HR-negative/HER2-positive, and 12% triple-negative (TN). Patients with HR-positive/HER2-negative tumors were older, had a lower grade and presented with the earlier stage (all P<0.0001). OS was significantly different according to TS in each stage (Pinteraction<0.0001). HR-positive/HER2-negative had the best OS in stage I (3-year OS, 97.2%). In contrast, HR-positive/HER2-positive had the best 3-year OS in stage II (94.5%), stage III (87.8%), and stage IV (54.8%). There was a 40.1% difference in OS at 3 years in stage IV between TN and HR-positive/HER2-positive. Multivariate analysis adjusted for age, race, grade, histology, and marital status confirmed these results. CONCLUSIONS: Although HR-positive/HER2-negative tumors had better clinicopathologic features, the HR-positive/HER2-positive group had the best OS in most stages. OS was significantly different by TS in each of the 4 stages and these results remained significant in the multivariate model.

Frequent ESR1 and CDK Pathway Copy-Number Alterations in Metastatic Breast Cancer.

DNA sequencing has identified a limited number of driver mutations in metastatic breast cancer beyond single base-pair mutations in the estrogen receptor (ESR1). However, our previous studies and others have observed that structural variants, such as ESR1 fusions, may also play a role. Therefore, we expanded upon these observations by performing a comprehensive and highly sensitive characterization of copy-number (CN) alterations in a large clinical cohort of metastatic specimens. NanoString DNA hybridization was utilized to measure CN gains, amplifications, and deletions of 67 genes in 108 breast cancer metastases, and in 26 cases, the patient-matched primary tumor. For ESR1, a copyshift algorithm was applied to identify CN imbalances at exon-specific resolution and queried large data sets (>15,000 tumors) that had previously undergone next-generation sequencing (NGS). Interestingly, a subset of ER+ tumors showed increased ESR1 CN (11/82, 13%); three had CN amplifications (4%) and eight had gains (10%). Increased ESR1 CN was enriched in metastatic specimens versus primary tumors, and this was orthogonally confirmed in a large NGS data set. ESR1-amplified tumors showed a site-specific enrichment for bone metastases and worse outcomes than nonamplified tumors. No ESR1 CN amplifications and only one gain was identified in ER- tumors. ESR1 copyshift was present in 5 of the 11 ESR1-amplified tumors. Other frequent amplifications included ERBB2, GRB7, and cell-cycle pathway members CCND1 and CDK4/6, which showed mutually exclusivity with deletions of CDKN2A, CDKN2B, and CDKN1B. IMPLICATIONS: Copy-number alterations of ESR1 and key CDK pathway genes are frequent in metastatic breast cancers, and their clinical relevance should be tested further.

Transcriptome Characterization of Matched Primary Breast and Brain Metastatic Tumors to Detect Novel Actionable Targets.

BACKGROUND: Breast cancer brain metastases (BrMs) are defined by complex adaptations to both adjuvant treatment regimens and the brain microenvironment. Consequences of these alterations remain poorly understood, as does their potential for clinical targeting. We utilized genome-wide molecular profiling to identify therapeutic targets acquired in metastatic disease. METHODS: Gene expression profiling of 21 patient-matched primary breast tumors and their associated brain metastases was performed by TrueSeq RNA-sequencing to determine clinically actionable BrM target genes. Identified targets were functionally validated using small molecule inhibitors in a cohort of resected BrM ex vivo explants (n = 4) and in a patient-derived xenograft (PDX) model of BrM. All statistical tests were two-sided. RESULTS: Considerable shifts in breast cancer cell-specific gene expression profiles were observed (1314 genes upregulated in BrM; 1702 genes downregulated in BrM; DESeq; fold change > 1.5, Padj < .05). Subsequent bioinformatic analysis for readily druggable targets revealed recurrent gains in RET expression and human epidermal growth factor receptor 2 (HER2) signaling. Small molecule inhibition of RET and HER2 in ex vivo patient BrM models (n = 4) resulted in statistically significantly reduced proliferation (P < .001 in four of four models). Furthermore, RET and HER2 inhibition in a PDX model of BrM led to a statistically significant antitumor response vs control (n = 4, % tumor growth inhibition [mean difference; SD], anti-RET = 86.3% [1176; 258.3], P < .001; anti-HER2 = 91.2% [1114; 257.9], P < .01). CONCLUSIONS: RNA-seq profiling of longitudinally collected specimens uncovered recurrent gene expression acquisitions in metastatic tumors, distinct from matched primary tumors. Critically, we identify aberrations in key oncogenic pathways and provide functional evidence for their suitability as therapeutic targets. Altogether, this study establishes recurrent, acquired vulnerabilities in BrM that warrant immediate clinical investigation and suggests paired specimen expression profiling as a compelling and underutilized strategy to identify targetable dependencies in advanced cancers.

Intrinsic Subtype Switching and Acquired ERBB2/HER2 Amplifications and Mutations in Breast Cancer Brain Metastases.

IMPORTANCE: Patients with breast cancer (BrCa) brain metastases (BrM) have limited therapeutic options. A better understanding of molecular alterations acquired in BrM could identify clinically actionable metastatic dependencies. OBJECTIVE: To determine whether there are intrinsic subtype differences between primary tumors and matched BrM and to uncover BrM-acquired alterations that are clinically actionable. DESIGN, SETTING, AND PARTICIPANTS: In total, 20 cases of primary breast cancer tissue and resected BrM (10 estrogen receptor [ER]-negative and 10 ER-positive) from 2 academic institutions were included. Eligible cases in the discovery cohort harbored patient-matched primary breast cancer tissue and resected BrM. Given the rarity of patient-matched samples, no exclusion criteria were enacted. Two validation sequencing cohorts were used-a published data set of 17 patient-matched cases of BrM and a cohort of 7884 BrCa tumors enriched for metastatic samples. MAIN OUTCOMES AND MEASURES: Brain metastases expression changes in 127 genes within BrCa signatures, PAM50 assignments, and ERBB2/HER2 DNA-level gains. RESULTS: Overall, 17 of 20 BrM retained the PAM50 subtype of the primary BrCa. Despite this concordance, 17 of 20 BrM harbored expression changes (<2-fold or >2-fold) in clinically actionable genes including gains of FGFR4 (n = 6 [30%]), FLT1 (n = 4 [20%]), AURKA (n = 2 [10%]) and loss of ESR1 expression (n = 9 [45%]). The most recurrent expression gain was ERBB2/HER2, which showed a greater than 2-fold expression increase in 7 of 20 BrM (35%). Three of these 7 cases were ERBB2/HER2-negative out of 13 ERBB2/HER2-negative in the primary BrCa cohort and became immunohistochemical positive (3+) in the paired BrM with metastasis-specific amplification of the ERBB2/HER2 locus. In an independent data set, 2 of 9 (22.2%) ERBB2/HER2-negative BrCa switched to ERBB2/HER2-positive with 1 BrM acquiring ERBB2/HER2 amplification and the other showing metastatic enrichment of the activating V777L ERBB2/HER2 mutation. An expanded cohort revealed that ERBB2/HER2 amplification and/or mutation frequency was unchanged between local disease and metastases across all sites; however, a significant enrichment was appreciated for BrM (13% local vs 24% BrM; P < .001). CONCLUSIONS AND RELEVANCE: Breast cancer BrM commonly acquire alterations in clinically actionable genes, with metastasis-acquired ERBB2/HER2 alterations in approximately 20% of ERBB2/HER2-negative cases. These observations have immediate clinical implications for patients with ERBB2/HER2-negative breast cancer and support comprehensive profiling of metastases to inform clinical care.