Mounting evidence supports a role for the immune system in breast cancer outcomes. The ability to distinguish highly immunogenic tumors susceptible to anti-tumor immunity from weakly immunogenic or inherently immune-resistant tumors would guide development of therapeutic strategies in breast cancer. Genomic, transcriptomic and clinical data from The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) breast cancer cohorts were used to examine statistical associations between tumor mutational burden (TMB) and the survival of patients whose tumors were assigned to previously-described prognostic immune subclasses reflecting favorable, weak or poor immune-infiltrate dispositions (FID, WID or PID, respectively). Tumor immune subclasses were associated with survival in patients with high TMB (TMB-Hi, P < 0.001) but not in those with low TMB (TMB-Lo, P = 0.44). This statistical relationship was confirmed in the METABRIC cohort (TMB-Hi, P = 0.047; TMB-Lo, P = 0.39), and also found to hold true in the more-indolent Luminal A tumor subtype (TMB-Hi, P = 0.011; TMB-Lo, P = 0.91). In TMB-Hi tumors, the FID subclass was associated with prolonged survival independent of tumor stage, molecular subtype, age and treatment. Copy number analysis revealed the reproducible, preferential amplification of chromosome 1q immune-regulatory genes in the PID immune subclass. These findings demonstrate a previously unappreciated role for TMB as a determinant of immune-mediated survival of breast cancer patients and identify candidate immune-regulatory mechanisms associated with immunologically cold tumors. Immune subtyping of breast cancers may offer opportunities for therapeutic stratification.

IMPORTANCE Management of the primary tumor site in patients with metastatic breast cancer remains controversial. OBJECTIVE To evaluate the patterns of receipt of initial breast surgery for female patients with stage IV breast cancer in the United States, with particular attention to women who survived at least 10 years. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study using data from the Surveillance, Epidemiology, and End Results (SEER) program. Female patients diagnosed as having stage IV breast cancer between 1988 and 2011 and who did not receive radiation therapy as part of the first course of treatment were included (N = 21 372). Kaplan-Meier estimates of median survival and descriptive statistics were used to compare patient and tumor characteristics by receipt of breast surgery at diagnosis. A Royston-Parmar survival model and logistic regression analysis assessed demographic and clinical factors associated with survival and prolonged survival (of at least 10 years). MAIN OUTCOMES AND MEASURES Differences in survival, particularly survival of at least 10 years, by receipt of initial surgery to the primary tumor. RESULTS Among the 21 372 patients, the median survival increased from 20 months (1988–1991) to 26 months (2007–2011). During this time, the rate of surgery declined (odds ratio [OR], 0.16; 95% CI, 0.12–0.21). Even so, receipt of surgery was associated with improved survival in multivariate analysis, which controlled for patient and clinical characteristics, along with time period (hazard ratio, 0.60; 95% CI, 0.57–0.63). For women diagnosed as having cancer before 2002 (n = 7504), survival of at least 10 years was seen in 9.6%(n = 353) and 2.9% (n = 107) of those who did and did not receive surgery, respectively (OR, 3.61; 95% CI, 2.89–4.50). In multivariate analysis, survival of at least 10 years was associated with receipt of surgery (odds ratio, 2.80; 95% CI, 2.08–3.77), hormone receptor–positive disease (OR, 1.76; 95% CI, 1.25–2.48), older age (OR, 0.41; 95% CI, 0.32–0.54), larger tumor size (OR, 0.37; 95% CI, 0.27–0.51), marital status of being separated at the time of diagnosis (OR, 0.67; 95% CI, 0.51–0.88), and more recent year of diagnosis (OR, 1.43; 95% CI, 1.02–1.99). CONCLUSIONS AND RELEVANCE Survival in stage IV breast cancer has improved and is increasingly of prolonged duration, particularly for some women undergoing initial breast surgery. As systemic therapy advances provide better control of distant disease in stage IV breast cancer, and as women present with lower distant disease burdens, these findings on initial surgery to the primary tumor may be of importance.

This population-based study reports recent outcomes, by receptor status, for women with metaplastic breast cancer. Survival in metaplastic breast cancer is not impacted by hormone receptor status. To the authors' knowledge, this is the first report indicating that women with human epidermal growth receptor 2 (HER2) positive metaplastic breast cancer have survival superior to women with HER2 negative metaplastic breast cancer and survival similar to women with HER2 positive invasive ductal carcinoma. This information can be used for counseling patients diagnosed with metaplastic breast cancer. Further understanding of HER2 positive metaplastic breast cancer could offer insights for the development of therapeutic approaches to metaplastic breast cancer more broadly.

PBL has increased in incidence over the last four decades and continues to increase for younger women and for some subtypes. The rise in imaging and procedures to the breast might enhance diagnostic sensitivity for PBL. Further study of the etiologies of PBL is needed.

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Background Although recent findings suggest that de novo stage IV breast cancer is increasing in premenopausal women in the United States, contemporary incidence and survival data are lacking for stage I–III cancer. Methods Women aged 20–29 (n = 3826), 30–39 (n = 34 585), and 40–49 (n = 126 552) years who were diagnosed with stage I–III breast cancer from 2000 to 2015 were identified from the Surveillance, Epidemiology, and End Results 18 registries database. Age-adjusted, average annual percentage changes in incidence and 5- and 10-year Kaplan-Meier survival curves were estimated by race and ethnicity, stage, and hormone receptor (HR) status and grade (low to well and moderately differentiated; high to poorly and undifferentiated) for each age decade. Results The average annual percentage change in incidence was positive for each age decade and was highest among women aged 20–29 years. Increased incidence was driven largely by HR+ cancer, particularly HR+ low-grade cancer in women aged 20–29 and 40–49 years. By 2015, incidence of HR+ low- and high-grade cancer each independently exceeded incidence of HR− cancer in each age decade. Survival for HR+ low- and high-grade cancer decreased with decreasing age; survival for HR− cancer was similar across age decades. Among all women aged 20–29 years, 10-year survival for HR+ high-grade cancer was lower than that for HR+ low-grade or HR− cancer. Among women aged 20–29 years with stage I cancer, 10-year survival was lowest for HR+ high-grade cancer. Conclusions HR+ breast cancer is increasing in incidence among premenopausal women, and HR+ high-grade cancer was associated with reduced survival among women aged 20–29 years. Our findings can help guide further evaluation of preventive, diagnostic, and therapeutic strategies for breast cancer among premenopausal women.

Purpose Recent findings suggest that combination treatment with anti-estrogen and anti-RET may offer a novel treatment strategy in a subset of breast cancer patients. We investigated the role of RET in potentiating the effects of anti-estrogen response and examined whether RET expression predicted the ability for tyrosine kinase inhibitor (TKI) to affect ERK1/2 activation in primary breast cancer. Experimental Design Growth response, ERK1/2 activation, Ki-67 and TUNEL were assessed in breast cancer cell lines in vitro and in xenografts with vandetanib and/or tamoxifen. Thirty tumors with matched normal breast tissue were evaluated for RET expression and response to TKI treatment. Results Vandetanib potentiated the inhibitory effect of tamoxifen in hormone responsive (p=0.01) and hormone insensitive (p<0.001) ERα-positive breast cancer cells. Vandetanib significantly repressed tumorigenesis of MCF-7 xenografts (p<0.001), which displayed decreased activation of ERK1/2 and AKT. Vandetanib and tamoxifen reduced the growth of established tumors with a greater effect of dual therapy compared to single agent (p=0.003), with tamoxifen reducing proliferative index and vandetanib inducing apoptosis. In primary breast cancers, RET expression correlated with the ERα-positive subtype. Relative decrease in ERK1/2 phosphorylation with TKI treatment was 42% (p<0.001) in RET-positive tumors vs. 14% (p=ns) in RET-negative tumors. Conclusions Vandetanib potentiated the anti-growth effects of tamoxifen in breast cancer, which was mediated through RET activation. RET predicted response to TKI therapy with minimal effects on ERK1/2 activation in RET-negative tumors. The preclinical data support evaluation of anti-estrogen in combination with TKI as a potential treatment strategy for RET-positive luminal breast cancer.

Background: Brain metastases are a major cause of death in patients with metastatic breast cancer. While surgical resection and radiation therapy are effective treatment modalities, the majority of patients will succumb from disease progression. We have developed a novel therapy for brain metastases that delivers athermal radiofrequency electromagnetic fields that are amplitude-modulated at breast cancer specific frequencies (BCF). Methods: 27.12 MHz amplitude-modulated BCF were administered to a patient with a breast cancer brain metastasis by placing a spoon-shaped antenna on the anterior part of the tongue for three one-hour treatments every day. In preclinical models, a BCF dose, equivalent to that delivered to the patient's brain, was administered to animals implanted with either brain metastasis patient derived xenografts (PDXs) or brain-tropic cell lines. We also examined the efficacy of combining radiation therapy with BCF treatment. Additionally, the mechanistic underpinnings associated with cancer inhibition was identified using an agnostic approach. Findings: Animal studies demonstrated a significant decrease in growth and metastases of brain-tropic cell lines. Moreover, BCF treatment of PDXs established from patients with brain metastases showed strong suppression of their growth ability. Importantly, BCF treatment led to significant and durable regression of brain metastasis of a patient with triple negative breast cancer. The tumour inhibitory effect was mediated by Ca 2+ influx in cancer cells through CACNA1H T-type voltage-gated calcium channels, which, acting as the cellular antenna for BCF, activated CAMKII/p38 MAPK signalling and inhibited cancer stem cells through suppression of β-catenin/HMGA2 signalling. Furthermore, BCF treatment downregulated exosomal miR-1246 level, which in turn decreased angiogenesis in brain environment. Therefore, targeted growth inhibition of breast cancer metastases was achieved through CACNA1H. Interpretation: We demonstrate that BCF, as a single agent or in combination with radiation, is a novel treatment approach to the treatment of brain metastases. This paradigm shifting modality warrants further clinical trials for this unmet medical need.