Disparities in Use of Human Epidermal Growth Hormone Receptor 2–Targeted Therapy for Early-Stage Breast Cancer

Trastuzumab is a key component of adjuvant therapy for stage I to III human epidermal growth factor receptor 2 (HER2)–positive breast cancer. The rates and patterns of trastuzumab use have never been described in a population-based sample. The recent addition of HER2 information to the SEER-Medicare database offers an opportunity to examine patterns of trastuzumab use and to evaluate possible disparities in receipt of trastuzumab