Adjuvant versus salvage radiation therapy for prostate cancer and the risk of death

Objective: To investigate whether salvage radiation therapy (RT) for prostate-specific antigen (PSA) failure can provide the same result as adjuvant RT, which decreases the risk of all-cause mortality (ACM) for men with positive margins (R1), or extra-capsular or seminal vesicle extension (pT3).

Methods: We studied 1638 men at Duke University who underwent radical prostatectomy for unfavourable-risk prostate cancer and whose postoperative PSA was undetectable. Cox regression was used to evaluate whether salvage vs adjuvant RT in men with a rapid (<10 months) or slow (≥10 months) PSA doubling time (DT) was associated with the risk of ACM, adjusting for adverse features (pT3, R1, Gleason score 8-10), age, preoperative PSA level, comorbidity and hormonal therapy use.

Results: Despite fewer men with two or more adverse features (61 vs 82%; P=0.016), salvage for a rapid PSA DT vs adjuvant RT increased the risk of ACM [adjusted hazard ratio (AHR)=3.42; 95% confidence interval (CI)=1.27-9.20; P=0.015]. There was no difference (AHR=1.39; 95% CI=0.50-3.90; P=0.53) in the risk of ACM among men who received salvage for a slow PSA DT or adjuvant RT. Nearly all (90%) men with a slow PSA DT had Gleason score ≤7 and the majority (59%) had at most pT3 or R1 disease.

Conclusion: Radiation therapy after PSA failure as compared with adjuvant RT was not associated with an increased risk of ACM in men with Gleason score ≤7 and pT3R0 or pT2R1 disease.