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

BACKGROUND AND

OBJECTIVE

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.

METHODS

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.

KEY FINDINGS AND LIMITATIONS: 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.

CONCLUSION AND CLINICAL IMPLICATIONS: 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.