Predictors of prostate cancer-specific mortality in elderly men with intermediate-risk prostate cancer treated with radiation therapy

9543 Background: To identify clinical factors associated with prostate cancer-specific mortality (PCSM), adjusting for co-morbidity, in elderly men with intermediate-risk prostate cancer treated with brachytherapy alone or in conjunction with external beam radiation therapy (EBRT). Methods: The study cohort comprised 1,978 men of median age 71 (interquartile range [IQR], 66–75) years with intermediate-risk prostate cancer (Gleason score 7 with PSA 20 ng/mL or less and tumor category T2c or less). Fine and Gray's multivariable competing risks regression was used to assess whether presence of cardiovascular disease (CVD), age, treatment, year of brachytherapy, PSA level, or tumor category were associated with the risk of PCSM. Results: After a median follow up of 3.2 (IQR, 1.7 - 5.4) years, 15 men were observed to experience PCSM. The presence of CVD was significantly associated with a decreased risk of PCSM (AHR 0.20, 95% CI 0.04 - 0.99, P = 0.05), whereas an increasing PSA level was significantly associated with an increased risk of PCSM (AHR 1.14, 95% CI 1.02 - 1.27, P = 0.02). In the absence of CVD, cumulative incidence estimates of PCSM were higher (P = 0.03) in men with PSA levels above as compared to the median PSA level (7.3 ng/mL) or less; however, in the setting of CVD there was no difference (P = 0.27) in these estimates stratified by the median PSA level (6.9 ng/mL). Conclusions: Detection of intermediate-risk prostate cancer in elderly men without CVD at lower PSA levels is associated with a lower risk of PCSM; this risk reduction is not observed in men with known CVD. [Table: see text] No significant financial relationships to disclose.