Impact of initial local therapy on survival in men later receiving chemotherapy for prostate cancer: a population-based, propensity-weighted multivariable analysis

Purpose: Prostate cancer remains a common disease that is frequently treated with multimodal therapy. The goal of this study was to assess the impact of treatment of the primary tumor on survival in men who go onto receive chemotherapy for prostate cancer. Methods: Using surveillance, epidemiology and end results (SEER)-Medicare data from 1992 to 2009, we identified a cohort of 1614 men who received chemotherapy for prostate cancer. Primary outcomes were prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM). We compared survival among men who had previously undergone radical prostatectomy (RP), radiation therapy (RT), or neither of these therapies. Propensity score adjusted Cox proportional hazard models and weighted Kaplan–Meier curves were used to assess survival. Results: Compared to men who received no local treatment, PCSM was lower for men who received RP ± RT (HR 0.65, p < 0.01) and for those who received RT only (HR 0.79, p < 0.05). Patients receiving neither RP nor RT demonstrated higher PCSM and ACM than those receiving treatment in a weighted time-to-event analysis. Men who received RP + RT had longer mean time from diagnosis to initiation of chemotherapy (100.7 ± 47.7 months) than men with no local treatment (48.8 ± 35.0 months, p < 0.05). Conclusion: In patients who go on to receive chemotherapy, treatment of the primary tumor for prostate cancer appears to confer a survival advantage over those who do not receive primary treatment. These data suggest continued importance for local treatment of prostate cancer, even in patients at high risk of failing local therapy.