Prognostic impact of definitive local therapy of the primary tumor in men with metastatic prostate cancer at diagnosis: A population-based, propensity score analysis

Background: This study investigated whether definitive local therapy [radical prostatectomy (RP) or brachytherapy (BT)] of the primary tumor improves survival in men with metastatic prostate cancer (PrCA) at diagnosis. Methods: Data on newly diagnosed metastatic PrCA cases (stage IV, N= 7858) were obtained from the Surveillance Epidemiology and End Results (SEER) program. Conventional multivariable survival analysis and propensity score analysis were used to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (95% CI) comparing men who underwent definitive local therapy of the primary tumor to those who did not. Results: After adjusting for sociodemographic and tumor attributes, having RP after diagnosis with metastatic PrCA was associated with 73% (HR. = 0.27, 95% CI: 0.20-0.38) lower risk of all-cause mortality and 72% (HR. = 0.28, 95% CI: 0.20-0.39) reduced risk of death from PrCA. Having BT also was associated with 57% (HR. = 0.43, 95% CI: 0.31-0.59) and 54% (HR. = 0.46, 95% CI: 0.33-0.64) lower risk of all-cause and PrCA-specific mortality. Similar results were observed in propensity score-adjusted analysis as well as when stratified by age and extent of tumor metastasis. Conclusions: These findings suggest that definitive local therapy improves survival in men with metastatic PrCA at diagnosis. Future work should consider comorbidities, diet, physical activity and smoking status.