[COST ANALYSIS OF ANDROGEN DEPRIVATION THERAPY AND DRUGS FOR CASTRATION-RESISTANT PROSTATE CANCER].

(Purpose) Recently, new effective drugs for the treatment of castration-resistant prostate cancer (CRPC) have been developed. Although they are expected to prolong the survival time of patients with advanced prostate cancer, they may result in an economic burden. In this study, we determined the treatment results and the cost of CRPC drugs. (Methods) From 2014 to 2017, patients who were unfit for curative therapy were enrolled in this study. First, they received androgen deprivation therapy (ADT) by surgical or chemical castration. Once castration-sensitive cancer progressed to castration-resistant cancer, CRPC drugs, such as docetaxel, cabazitaxel, abiraterone and enzalutamide, were administered sequentially. In elderly or fragile patients, drug doses were often reduced to minimize their toxicity. The total costs of drugs for castration-sensitive and castration-resistant cancers were calculated, and the results were evaluated. (Results) Prostate biopsies detected prostate cancer in 257 patients. Eighty-one patients were treated with ADT, and 56 of the cancers were metastatic or showed a high prostate specific antigen level (>100 ng/ml). Thirty patients out of the 56 with advanced cancers developed CRPC, and the median time to CRPC was 10 months (range, 3-39). Drugs targeting CRPC were administered in 25 patients for a median duration of 20 months (range, 3-50). During the median observation period of 48 months (range, 13-75), 15 patients died of prostate cancer. The median annual cost of drugs for castration-sensitive cancer was 234,000 Japanese yen (2,187 US dollars) [range, 50,000-315,000 yen (467-2,943 US dollars) ]. In contrast, the median annual cost of drugs for CRPC was 2,041,000 yen (19,075 US dollars) [range, 346,000-5,017,000 yen (3,230-46,886 US dollars) ]. (Conclusions) Advanced prostate cancer tended to rapidly progress to CRPC, which required a sequence of expensive drugs for treatment. Early diagnosis preventing the development of advanced prostate cancer is desirable to reduce the economic burden for the health insurance system.