Impact of prior local therapy on overall survival in men with metastatic castration-resistant prostate cancer: Results from Shared Equal Access Regional Cancer Hospital.

OBJECTIVES: To evaluate the impact of previous local treatment on survival in men with newly diagnosed metastatic castration-resistant prostate cancer. METHODS: We carried out a retrospective study of patients newly diagnosed with metastatic castration-resistant prostate cancer in the year 2000 or later from eight Veterans Affairs Medical Centers. Patients were categorized based on prior local therapy (none, prostatectomy ± radiation or radiation alone). Overall and cancer-specific survival was estimated by the Kaplan-Meier method. Cox proportional hazards regression models were used to test the association between prior local treatment and survival. RESULTS: Of 729 patients, 284 (39%) underwent no local treatment, 176 (24%) underwent radical prostatectomy ± radiation and 269 (37%) underwent radiation alone. On multivariable analysis, men with prior prostatectomy had improved overall (hazard ratio 0.71, P = 0.005) and cancer-specific survival (hazard ratio 0.55, P < 0.001) compared with men with no prior local therapy. This improvement in overall (hazard ratio 0.89, P = 0.219) and cancer-specific survival (hazard ratio 0.87, P = 0.170) was not seen in men with prior radiation alone. After further adjusting for comorbidity with the Charlson Comorbidity Index, patients with prior prostatectomy still had improved overall survival (hazard ratio 0.70, P = 0.003), whereas this was not seen in patients who received prior radiation alone (hazard ratio 0.88, P = 0.185). CONCLUSIONS: Independent of patient- and disease-related factors, men with metastatic castration-resistant prostate cancer who had undergone prior radical prostatectomy have improved overall and cancer-specific survival compared with those with no prior local therapy.