Importance of androgen-deprivation therapy during enzalutamide treatment in men with metastatic castration-resistant prostate cancer following chemotherapy: results from retrospective, multicenter data

Background: Enzalutamide can significantly prolong the survival of patients with metastatic castration-resistant prostate cancer (mCRPC). However, there is a paucity of evidence on continuing androgen-deprivation therapy (ADT) for mCRPC. Here, we analyzed the effect of concomitant ADT during enzalutamide treatment in men with mCRPC following chemotherapy. Methods: We retrospectively reviewed the medical records of 232 patients with mCRPC who received oral enzalutamide (160 mg per day) following chemotherapy at 9 tertiary centers in Korea between 2014 and 2016. The primary endpoint was overall survival, while secondary endpoints included time to prostate-specific antigen (PSA) progression and radiographic progression-free survival. Results: The median age of the patients was 71 years (interquartile range, 64–75 years). The proportion of patients in a grade group ≥4 was 77.6%. The rate of concomitant ADT was 29.3%, and the all-cause mortality rate was 27.1% (n = 63). Median overall survival, time to PSA progression, and radiographic progression-free survival were 24.0, 8.0, and 10.0 months, respectively. Notably, concomitant ADT showed a significant association with longer overall survival (median duration not reached vs. 18.2 months; p = 0.008). After adjusting for confounding factors, concomitant ADT was still associated with longer overall survival (hazard ratio, 0.35; 95% confidence interval, 0.17–0.72). Conclusion: Concomitant ADT during enzalutamide treatment may improve the survival of patients with mCRPC following chemotherapy.