Bone-targeted agent treatment patterns and the impact of bone metastases on patients with advanced breast cancer in the United States.

Bone metastases are common among patients with advanced breast cancer, putting patients at increased risk of skeletal-related events (SREs). This study described impact of bone metastases, utilization of bone-targeted agents (BTAs) and physicians' decision processes for BTA use in advanced breast cancer. Data were collected using the Adelphi Breast Cancer Disease-Specific Programme in the United States. Physicians completed a detailed record for eligible patients (women ≥18 years, with stage IIIB-IV breast cancer). Data available from 1276 patients with advanced breast cancer included 485 (38%) with bone metastases. Most (80%) reported pain at bone metastasis diagnosis; of those reporting pain, 55% reported moderate to severe pain. Among patients with bone metastasis, 69% received a BTA. Reasons for initiating BTAs were bone pain (32%) and an estimated high risk of SREs (25%). Reasons for not treating with BTAs were very recent diagnosis (37%), poor Karnofsky performance status (14%), perceived low risk of SREs (11%) and short life expectancy (11%). Zoledronic acid (48%) and denosumab (42%) were commonly used BTAs; the main reasons for initiating BTA treatment were long-term safety (28% and 32%, respectively) and efficacy in delaying SREs (15% and 31%, respectively). The analysis was not adjusted for age or other possible confounders. Bone pain is a common and sometimes severe symptom of bone metastases in advanced breast cancer and a common reason for initiating BTA treatment. Safety and efficacy were the main factors considered by physicians when selecting BTAs.