In a study in a German cohort reported in the Journal of Clinical Oncology, Tilki et al found that adjuvant radiation therapy was associated with reduced all-cause mortality vs early salvage radiation therapy after radical prostatectomy among men with pN1 prostate cancer. The benefit increased with an increasing number of positive pelvic lymph nodes and was greatest among those with four or more positive lymph nodes.
The study included prospectively collected data from 17,913 men with pT2–4N1M0 disease consecutively treated between March 1995 and October 2017 with radical prostatectomy and pelvic lymph node assessment at the University Hospital Hamburg-Eppendorf and followed for treatment with adjuvant radiation therapy or early salvage radiation therapy. The last update of the database was completed in October 2020.
In the cohort:
The median time from surgery was 3.42 months for adjuvant radiation therapy and 21.36 months for early salvage radiotherapy. Multivariate analysis for all-cause mortality, measured from date of radical prostatectomy, was adjusted for disease prognostic factors, age at radical prostatectomy, number of positive pelvic lymph nodes, number of lymph nodes sampled, and time-dependent use of post–radical prostatectomy adjuvant or salvage androgen-deprivation therapy.
After a median follow-up of 7.02 years, 986 men (5.5%) men died, with 223 (22.6%) dying from prostate cancer.
Adjuvant vs early salvage radiotherapy was associated with a significantly reduced risk of all-cause mortality (286 deaths), with an adjusted hazard ratio (HR) of 0.92 (95% confidence interval [CI] = 0.85–0.99, P = .03) for each additional positive pelvic lymph node—ie, an 8% reduction in risk per lymph node. No significant difference was found for no radiotherapy vs early salvage radiotherapy (923 deaths; adjusted HR = 0.99, 95% CI = 0.94–1.04, P = .66).
Adjusted 7-year all-cause mortality estimates were 7.74% for adjuvant radiation therapy vs 23.36% for early salvage radiotherapy (difference = 15.62%, 95% CI = 5.90%–25.35%) among patients with four or more positive lymph nodes. Estimates were 14.27% vs 13.89% (difference = 0.38, 95% CI = –7.02% to 7.79%) among those with one to three positive lymph nodes.
No significant differences between 7-year adjusted all-cause mortality estimates were observed between no radiotherapy vs early salvage radiotherapy among patients with one to three positive lymph nodes (13.27%; difference = 0.62%, 95% CI = –5.21% to 6.45%) or those with four or more positive lymph nodes (33.67%; difference = 10.31%, 95% CI = –1.85% to 22.47%).
The investigators concluded, “Adjuvant compared with early salvage radiotherapy in men with pN1 prostate cancer was associated with a decreased all-cause mortality risk, and this reduction increased with each additional positive pelvic lymph node.”
Disclosure: No funding for the study was reported. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.