Overall survival advantage with radical prostatectomy for prostate cancer.
37 Background: To compare overall survival of patients who underwent radical prostatectomy or radiotherapy versus non-cancer controls in order to discern if there is a survival advantage according to prostate cancer treatment. Methods: A matched cohort study was performedusingthe Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database. We identified 34,473 patients age 66 to 75 years without significant comorbidity from who were diagnosed with localized prostate cancer treated with surgery or radiotherapy between 2004 and 2011. These patients were matched to a non-cancer control cohort. We compared the rates of all-cause mortality that occurred within the study period. We used Cox Proportional Hazards Regression analysis to identify determinants associated with overall survival. Results: Of the total 34,473 patients who were included in the analysis, 21,740 (63%) received radiation therapy and 12,733 (37%) received surgery. When compared to the non-cancer control, there was no significant difference between the prostate cancer cohort and the non-cancer control group with exception of race/ethnicity (p < 0.001). There was improved survival in patients treated with surgery (hazard ratio [HR], 0.35; 95% CI, 0.32-0.38) as well as with radiotherapy (HR, 0.72; 95% CI, 0.68-0.75) when compared to non-cancer controls. There was significantly improved overall survival among both treatment groups with most benefit observed among patients who underwent surgery ( log rank p < 0.001). Conclusions: Using population based data, treatment with either surgery or radiotherapy demonstrated improved overall survival when compared to a cohort of matched non-cancer controls. Treatment with surgery resulted in longer overall survival compared to those receiving radiation therapy. These results suggest inherent selection-bias due to unmeasured confounding variables when using cancer registry data.