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

Abstract

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). 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. 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. 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.