Postoperative Pelvic Lymph Node Radiation Therapy in Lymph Node-Positive Prostate Cancer and Mortality Risk

Whether including pelvic lymph nodes in postradical prostatectomy (RP) radiotherapy (RT) volume for patients with pathologically node-positive (pN1) prostate cancer (PC) is associated with differences in mortality remains uncertain.

Multivariable Cox and Fine-Gray regression analyses were performed to evaluate whether use of whole-pelvic lymph node RT (WPRT) plus prostate bed RT (PBRT), compared with PBRT alone, was associated with all-cause mortality (ACM) and PC-specific mortality (PCSM) in this retrospective single-institution cohort of 816 patients with pT2-4pN1M0 PC treated with RP after adjusting for age at and year of RT delivery, pre-RT prostate-specific antigen level, pGleason score, pTumor stage, surgical margin status, number of removed and positive pelvic lymph nodes, and time-dependent use of androgen deprivation therapy. Covariate-adjusted estimates of ACM were generated using the extended Kaplan-Meier method.

After a median follow-up of 4.83 yr (interquartile range: 3.84-5.90), the addition of WPRT to the postoperative RT treatment volume was associated with a significantly reduced ACM risk (adjusted hazard ratio [AHR], 0.30; 95% confidence interval [CI], 0.17-0.52; p < .001) and PCSM-risk (AHR, 0.42; 95% CI, 0.19-0.91; p = .03) compared with PBRT alone. Key limitations include the retrospective single-institution design, evolving systemic therapies, and limited PSMA positron emission tomography imaging.

WPRT was associated with lower risks of ACM and PCSM among patients receiving postoperative RT for pN1 PC. These findings warrant further investigation in appropriately designed prospective studies.