Treatment patterns of castration-resistant prostate cancer: A retrospective claims database analysis.

Abstract

198 Background: Prostate cancer is the most commonly diagnosed malignancy among men in the US; mortality rates are highest among those with castration-resistant prostate cancer (CRPC). Observational data on CRPC are limited. This study examined CRPC treatment patterns relative to NCCN guidelines in a large US health plan. Methods: This was a retrospective claims database analysis of commercial and Medicare Advantage enrollees with evidence of prostate cancer (ICD-9: 185.xx) between 07/01/06 – 03/31/11. CRPC patients were then identified based on prostate-specific antigen (PSA) progression (≥2 PSA increases based on ≥3 PSA values) and/or use of chemotherapy: docetaxel (DOC), mitoxantrone (MIT), estramustine (EST), or cabazitaxel (CAB). The CRPC index date was the first date of PSA progression or chemotherapy. Patients were continuously enrolled for 6 months before (baseline) and ≥6 months after the index date until 09/30/2011 or until death, if sooner (follow-up). Results: A total of 1651 patients met the CRPC selection criteria. Mean (SD) age was 70 ± 9 years, 1085 (66%) received DOC on the index date, and 467 (28%) died during follow-up. A third of patients with DOC received additional CRPC therapy during follow-up: 160 (15%) received MIT, EST, or CAB, and 239 (22%) received a secondary hormonal therapy (SHT: antiandrogens, aminoglutethimide, GnRH/LHRH antagonists, estrogen, or abiraterone acetate). Among 566 patients without DOC, 99 (17%) received a different chemotherapy (MIT = 45; EST = 52; CAB = 2), and 178 (31%) received a SHT. More than half 311 (55%) without DOC did not receive any other CRPC therapy during follow-up, of which 40 (13%) received bone-directed therapy (BDT: denosumab = 0; bisphosphonates = 27; radiation = 13). Conclusions: Consistent with NCCN guidelines, DOC was the most commonly used therapy. However, two-thirds of patients with DOC and over half of patients without DOC did not receive additional CRPC therapy after the index date. In addition, only 13% of patients with no CRPC therapy received any follow-up BDT. Additional research is warranted to understand whether clinical rationale, patient preference, or access to care may have resulted in patients not receiving additional therapy.