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

Aim: We evaluated outcomes of first-line (1L) treatment of metastatic breast cancer (mBC) by biomarker subtype in the community setting over the last decade. Methods: Eligible patients (N = 1,518) were female, ≥18 years, diagnosed with mBC 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 (rwPFS) and overall survival (OS) from start of 1L. Results: TNBC was diagnosed at an earlier stage and had higher tumor grade at initial diagnosis. 1L rwPFS and OS from start of 1L were shorter for TNBC than HR+/HER2- or HER2+. Conclusion: Overall prognosis for patients with metastatic TNBC remains poor, and new therapies are needed to improve clinical outcomes.