The role of adjuvant radiotherapy in pathologically lymph node-positive prostate cancer

Background: Postoperative management of prostate cancer with lymph node involvement (LNI) is controversial. Retrospective evidence supports the selective use of radiotherapy (RT) after extended pelvic lymph node dissection. It is unclear whether this is generalizable to practice in the United States, where extended dissection is uncommon. The authors identified patients with LNI who potentially could derive a survival benefit with adjuvant RT plus androgen-deprivation therapy (ADT).

Methods: Patients with N1M0 prostate adenocarcinoma who underwent radical prostatectomy (RP) and subsequently received ADT from 2003 through 2011 were identified from the National Cancer Database. Kaplan-Meier analyses, log-rank tests, and multivariable Cox proportional hazards regression were performed using overall survival (OS) as the primary outcome.

Results: In total, 906 of 2569 eligible patients (35.3%) received RT, and RT was more frequently received by patients who were diagnosed in later years, had fewer positive lymph nodes, had involved surgical margins, and were aged <65 years (all P < .05). The 5-year OS rate was 87% versus 82% in those who received RT versus those who did not (P = .007). After propensity score matching, 826 patients remained in each cohort. RT retained an association with OS (5-year OS: 88% vs 81%; P = .009; hazard ratio, 1.43; 95% confidence interval, 1.10-1.86; P = .008). No interaction was identified between the effect of RT on OS across tested strata of total lymph nodes examined, lymph node ratio, total number of positive lymph nodes, margin status, Gleason score, and prostate-specific antigen.

Conclusions: RT plus ADT was associated with improved OS after RP in patients with LNI. These results may help guide therapy in the absence of randomized evidence. Cancer 2017;123:512-520. © 2016 American Cancer Society.