Current Status of Sequential Treatment for Castration-resistant Prostate Cancer: A Retrospective Analysis.

Background/aim: Although multiple treatments are available for metastatic castration-resistant prostate cancer, data to determine the optimal treatment sequence are limited. This study aimed to investigate the current status of drug therapy for castration-resistant prostate cancer and clarify the sequential treatment in actual clinical practice.

Patients and methods: This retrospective study included 425 patients diagnosed with castration-resistant prostate cancer at Showa University Hospital and affiliated hospitals between January 2014 and December 2021, who were treated with any of the following four drugs: novel androgen receptor signal inhibitors (abiraterone acetate and enzalutamide) and anticancer drugs (docetaxel and cabazitaxel). We investigated the actual treatment choices for castration-resistant prostate cancer, focusing on the order of administration of the four drugs. This analysis was visualized using a Sankey diagram.

Results: Regarding the number of drugs administered, most patients received one type of drug, with androgen receptor signal inhibitors being the most commonly administered (total, 179; enzalutamide, 139 and abiraterone acetate, 40). Enzalutamide was the most frequently selected first-line drug (58.4%). The most common sequence for second-line treatment was androgen receptor signal inhibitor-androgen receptor signal inhibitor (n=96), followed by androgen receptor signal inhibitor-docetaxel (n=85), docetaxel-androgen receptor signal inhibitor (n=59), and docetaxel-cabazitaxel (n=6).

Conclusion: Androgen receptor signal inhibitors is the most commonly used drug category for first-line treatment of castration-resistant prostate cancer, with enzalutamide being the most commonly used drug. Further investigations are required regarding patient background and prognosis.