BACKGROUND: Endocrine therapy (ET) remains a foundation of systemic therapy for HR+/HER2- metastatic breast cancer (MBC), although chemotherapy (CT) is used in select patients. In this "real-world" study, we explored treatment patterns, health care resource use (HCRU), costs, adverse events (AEs), and overall survival (OS) in Medicare-enrolled, older patients with HR+/HER2- MBC.
METHODS: Patients with HR+/HER2- MBC (2007-2011) and aged >66 years were retrospectively analyzed using the SEER-Medicare data. Treatment patterns, HCRU, costs, AEs, and OS after MBC diagnosis through end of study period (December 31, 2013) were examined using descriptive and multivariable analyses.
RESULTS: Among 3,622 eligible patients, ET was the most common treatment (77%), followed by CT (50%), radiation (48%), and surgery (19%). The proportion of patients treated with ET monotherapy decreased across therapy lines, from 74% in first line (1L) to 35% in 4L. The total number of unique therapy regimens used was 181 in 1L, 171 in 2L, 128 in 3L, and 95 in 4L. The median OS from MBC diagnosis was 25.3 months (95% CI, 24.0-26.7). In multivariable analyses, receipt of CT and combination CT + ET (versus ET monotherapy) in 1L, metastatic disease at initial diagnosis, larger tumor size, and presence of visceral and brain metastases at MBC diagnosis significantly predicted receipt of 2L therapy.
CONCLUSIONS: ET was the most common first-line treatment for study patients, but its use decreased gradually in the subsequent lines. The heterogeneity in the treatment selection highlights a lack of consensus for the management of HR+/HER2- MBC in routine practice.
