Real-world outcomes in metastatic HR+/HER2-, HER2+ and triple negative breast cancer after start of first-line therapy.

We evaluated outcomes of first-line (1L) treatment of metastatic breast cancer by biomarker subtype in the community setting over the last decade. Eligible patients (n = 1518) were female, ≥18 years, diagnosed with metastatic breast cancer 2010 or later, had documented HR+/HER2-, HER2+, or triple negative breast cancer (TNBC); and initiated 1L therapy. Kaplan-Meier and Cox methods were used to evaluate 1L real-world progression-free survival and overall survival from start of 1L. TNBC was diagnosed at an earlier stage and had higher tumor grade at initial diagnosis. 1L real-world progression-free survival and overall survival from start of 1L were shorter for TNBC than HR+/HER2- or HER2+. Overall prognosis for patients with metastatic TNBC remains poor, and new therapies are needed to improve clinical outcomes.