Analysis of competing risk parameters in irradiated prostate cancer patients

Purpose: Retrospective competing risk analysis of prognostic factors in definitive-irradiated prostate cancer patients. Patients and Methods: Data of 652 patients were analyzed according to three age subgroups (< 65, 65 ≤ 75, > 75 years; Table 1). Pre-RT PSA values (median 13.4 ng/ml) were available for 340 patients. Adjuvant hormone therapy (n = 261) consisted either of orchiectomy (n = 151) or LHRH agonist with/without antiandrogen therapy or in the early years, diethystilbestrol. Neoadjuvant hormone therapy (n = 31) using LHRH agonists was given 6 months before and during radiotherapy. Results: Biochemical failure was observed in 69/340 patients, 5 years after biochemical failure, 64.9% of them also had failed clinically. The cumulative incidence of local failure (LF) and distant metastases (DM) was 9.4% and 37.2%, respectively; LF and DM at the same time were seen in 18.2%. On multivariate analysis (Tables 2 and 3), advanced stage (relative risk [RR] 4.54), pre-RT PSA > 20 ng/ml (RR 2.79) and poorly differentiated tumors (RR 2.96) were significant predictors of biochemical failure. Advanced stage increased the risk of LF (RR 2.18), DM (RR 3.66), and prostate cancer death (PCD; RR 4.30). Hormone therapy decreased the risk of biochemical failure (RR 0.67), DM (RR 0.59), and PCD (RR 0.60) without reaching statistical significance. Median follow-up was 7.6 years. Conclusion: Risk of biochemical failure was predicted by pre-RT PSA, stage, and grade; in patients with biochemical failure, the cumulative incidence of death from intercurrent diseases and PCD was 25.0% and 29.2% after 5 years, respectively. The risk of DM and PCD was predicted by stage and grade. Higher age (> 75 years) decreased the relative risk of LF, DM, and PCD significantly.