Treatment patterns and survival in metastatic castration‐sensitive prostate cancer in the US Veterans Health Administration

BACKGROUND: Limited real‐world data exist on treatment patterns and outcomes in patients with metastatic castration‐sensitive prostate cancer (mCSPC). METHODS: A retrospective cohort study was conducted, using the Veterans Health Administration claims database (April 2013–March 2018). Among 369,734 prostate cancer patients, we selected all men who developed metastases within 90 days before or after medical/surgical castration and who received androgen deprivation therapy (ADT). Patients were categorized into four cohorts: ADT‐only (± <90‐day nonsteroidal anti‐androgen [NSAA] use), ADT + NSAA, ADT + docetaxel, and ADT + abiraterone. Main outcomes were treatment patterns, time‐to‐progression to metastatic castration‐resistant disease, and overall survival. Multivariable analysis and sensitivity analysis were conducted. RESULTS: Of 1395 patients, 874 (63%) received ADT‐only, 338 (24%) received ADT + NSAA, 108 (8%) received ADT + docetaxel, and 75 (5%) received ADT + abiraterone. Proportions on ADT‐only and ADT + NSAA declined (from 66% to 60% and from 31% to 17%, respectively) over the study period, while proportions prescribed ADT + docetaxel or abiraterone increased from 3% to 9% and from 1% to 15%, respectively. Patients treated with ADT + NSAA had similar risks of castration‐resistant disease (hazard ratio [HR] 1.05; 95% confidence interval [CI]: 0.87, 1.26) and overall mortality (HR 1.22; 95% CI: 0.97, 1.54) as ADT‐only. CONCLUSIONS: Most patients with mCSPC initiating ADT received ADT‐only or ADT + NSAA, despite the emergence of docetaxel and novel hormonal therapies. Even in the most recent period (2017 to early 2018), only 24% of men received intensified therapy with agents known to prolong survival versus ADT‐only. These data in real‐world clinical practice suggest substantial room for improved outcomes in patients with mCSPC.