Updates in the treatment of HR+HER2-breast cancer

Purpose of review Breast cancer (BC) is the most common cancer among women in the United States and the second leading cause of cancer death. BC research, diagnostics, drug development, and expansion of therapies for novel indications advances so rapidly that BC treatment standards change month-by-month. Herein we discuss notable advancements in the past year for hormone receptor positive (HR+) HER2 negative (HER2-) BC. Recent findings Radiolabeled estradiol imaging and circulating tumor DNA (ctDNA) have changed our approach to metastatic BC (mBC) detection. Amongst an abundance of therapy options, treatment de-escalation to avoid toxicities is a priority. Promising results with CDK4/6 inhibitors in the curative setting have been demonstrated even as we await final data for use in the metastatic setting. Several novel endocrine therapies are expected to gain FDA-approval in the near future. Antibody-drug conjugates have expanded from other mBC types to HRthornHER2-mBC. The PROMISE trial helped define disease recurrence outcomes for premenopausal women seeking pregnancy. Summary The diagnostic and treatment landscape for HR+ HER2-BC continues to rapidly evolve on multiple fronts.