Strategy for PSA progression in patients undergoing salvage radiation for biochemical recurrence after radical prostatectomy

Background The treatment strategy for prostate-specific antigen (PSA) progression in patients who receive salvage radiation therapy (RT) for biochemical recurrence (BCR) after radical prostatectomy (RP) is salvage androgen deprivation therapy (ADT). However, its optimal timing is highly controversial. Methods The study sample consisted of 77 men who underwent RP, received salvage RT against BCR, and underwent salvage ADT for PSA progression. The endpoint of this study was development to castration-resistant prostate cancer (CRPC), from the start of salvage RT. Results The median follow-up time was 9.5 years, and 20 patients experienced CRPC. The multivariable analysis identified PSA-doubling time (PSA-DT) ≤ 12 months (hazard ratio, 3.5) and seminal vesicle invasion (SVI) (hazard ratio, 4.4) as independent risk factors. We defined the high-risk and low-risk groups as those with one or two risk factors and no risk factors, respectively. In the high-risk group, a significant difference in time to CRPC was observed between patients who received salvage ADT at PSA ≤ 1.0 ng/mL ( n = 8) and at > 1.0 ng/mL ( n = 27) (10-year non-CRPC rate: 100.0% vs. 46.3%, respectively). In contrast, in the low-risk group, no significant difference in CRPC-free survival was observed between patients who received salvage ADT at PSA ≤ 1.0 ng/mL ( n = 14) and at > 1.0 ng/mL ( n = 28) (10-year non-CRPC rate: 86.4% vs. 80.8%, respectively). Conclusion In high-risk patients (PSA-DT ≤ 12 months and/or SVI), salvage ADT for PSA progression after salvage RT should be started before the PSA levels exceed 1.0 ng/mL.