Post-operative pelvic lymph node radiation therapy in lymph node positive prostate cancer and mortality risk.

Abstract

117 Background: Whether including pelvic lymph nodes in post-radical prostatectomy (RP) radiotherapy (RT) volume for patients with pathologically node-positive (pN1) prostate cancer (PC) reduces mortality is unknown and was investigated. Methods: Multivariable Cox regression was used to evaluate whether a significant association existed between all-cause mortality (ACM)-risk and time-dependent use of whole pelvic lymph node RT (WPRT) plus prostate bed RT (PBRT) versus PBRT alone among the 816 patients with pT2-4pN1M0 PC treated with RP of which 48.65% had prostatectomy (p)Gleason score 8-10, after adjusting for age at and year of RT delivery, pre-RT PSA level, pGleason score, pTumor stage surgical margin status, number of removed and positive pelvic lymph nodes, and time-dependent use of androgen deprivation therapy. Both fixed and time-dependent covariates adjusted estimates of ACM were generated using the extended Kaplan–Meier method. Results: After a median follow-up of 4.83 years (Interquartile range: 3.84-5.90), of the 816 patients in the study cohort, 119 (14.58%) died, including 58 (48.74%) were from PC. The addition of WPRT to the post-operative RT treatment volume was associated with a significantly reduced ACM-risk compared with PBRT alone (adjusted HR, 0.31; 95% CI, 0.18 to 0.55; P < .001). Conclusions: WPRT has the potential to reduce mortality-risk in patients with pN1 PC.