Neoplasms of the Breast

Abstract

Overview Breast cancer is the most common cancer among women in the United States and growing in incidence worldwide, while mortality due to breast cancer is slowly decreasing. The last two decades have witnessed many changes in the diagnostic landscape both in terms of imaging studies and laboratory tests, most notably next‐generation sequencing both on tumor and blood. Our understanding of breast oncogenesis, tumor heterogeneity, and metastasis has deepened. Segmental mastectomy and sentinel lymph node (SLN) biopsy have been used in the majority of cases coupled with radiation therapy. In cases managed with mastectomy, radiation of one to three positive nodes has been utilized more often. Gene expression profiling has been used to identify women with hormone receptor‐positive (HR+) breast cancer who would benefit from adjuvant chemotherapy. Targeted therapy has been developed for HR+, HER2 amplified, and triple‐negative breast cancer. Immune checkpoint inhibitors have improved the management of triple‐negative disease. poly(adenosine diphosphate [ADP]–ribose) (PARP) inhibitors have improved outcomes for breast cancer patients with BRCA1/2 mutations. Combinations of targeted therapies and hormonal therapies have proved effective for adjuvant therapy and in recurrent disease.