Comparison of the clinical outcome after hormonal therapy for prostate cancer between Japanese and Caucasian men

OBJECTIVE: To investigate the impact of race on the effectiveness of hormonal therapy in patients with prostate cancer, by comparing the outcomes of Caucasian men (CM) and Japanese-American men (JAM) treated with hormonal therapy at one institution. PATIENTS AND METHODS: Fifty-nine CM and 105 JAM with prostate cancer were treated with hormonal therapy at The Queen's Medical Center in Honolulu. Age, stage, Gleason score, race, and pretreatment PSA levels were abstracted. The Kaplan-Meier method was used to construct overall and cause-specific survival curves, which were compared using log-rank statistics. These factors were assessed as to their interdependence and correlation with the clinical course using a Cox proportional hazards regression model. RESULTS: Although there were no statistical differences in patient background, JAM who had received hormonal treatment had a better outcome than CM for overall and cause-specific survival rate (P = 0.001 and 0.036, respectively). Race was one of the significant prognostic factors in the multivariate analysis (P = 0.03). The findings suggest a difference in the effectiveness of hormonal therapy for prostate cancer in JAM living in Hawaii compared to CM. CONCLUSIONS: There were marked racial differences in clinical outcome after hormonal therapy between JAM and CM. A prospective study with more patients might be necessary to elucidate the differential effectiveness of hormonal therapy for prostate cancer in different races, especially between Japanese and Caucasians.