BACKGROUND: Therapeutic advances in metastatic breast cancer (MBC) over the last decade have led to several novel agents for the treatment of patients with hormone receptor positive (HR+)/HER2– MBC. However, current literature has little data on real-world treatment patterns and health care resource use, particularly among elderly women with HR+/HER2– MBC in the United States Medicare population.
METHODS: A retrospective analysis of patients aged ≥66 years diagnosed with MBC during 2007 to 2011 was conducted using the SEER-Medicare database. Patients’ HR and HER2 status was obtained from the SEER registry data. For patients with no HER2 data available, HER2− disease was determined based on the absence of HER2-targeted therapies within 12 months of diagnosis. Health care utilization and treatment patterns after MBC diagnosis were examined. Use of cancer-directed therapies, including chemotherapy (CT) and endocrine therapy (ET), were descriptively analyzed by line of therapy (LOT).
RESULTS: A total of 3,622 women with HR+/HER2– MBC (mean [SD] age, 77 [7.3] years) were included. Over 90% of women received ≥1 cancer-directed treatment after MBC diagnosis, with ET being the most common (77%), followed by CT (50%), radiation (48%), and surgery (19%). Treatment with ET alone trended downward across LOTs, from 74% in the first LOT to 36% in the fourth LOT, with a corresponding increase in treatment with CT alone from 21% to 46% (Table 1). Among those receiving a second LOT, nearly 26% switched to CT in the second line after having received ET alone in the first line.
CONCLUSIONS: ET was the most common first-line treatment for elderly women with HR+/HER2– MBC in this study period. However, as patients progressed from first to fourth LOT, the proportion of patients treated with ET decreased substantially.
