Two subgroups of men with node-positive prostate cancer are more likely to benefit from adjuvant radiotherapy after surgery than others, investigators report online in the Journal of Clinical Oncology.
A retrospective observational study of 1,107 patients receiving adjuvant hormonal therapy with or without radiotherapy, found that men with one or two positive lymph nodes and intermediate- to high-grade, non–specimen-confined disease, and men with three or four positive nodes regardless of other tumor characteristics, saw significantly improved cancer-specific mortality at 8 years associated with radiotherapy (hazard ratio, 0.30; P = .002 for the former and HR, 0.21; P = .02, for the latter). Adjuvant radiotherapy did not improve survival in patients with extremely favorable (two or fewer positive lymph nodes, specimen-confined, and/or low-grade tumor) or extremely unfavorable (greater than four positive nodes) prostate cancer.
Investigators, led by Dr. Firas Abdollah of the Mayo Clinic, Rochester, Minn., looked at the records of patients treated between 1988 and 2010 at the Mayo Clinic and San Raffaele Hospital in Milan, Italy, with radical prostatectomy and anatomically extended pelvic lymph node dissection before being treated with adjuvant hormonal therapy, and adjuvant radiotherapy at the discretion of the physician (35% of the cohort received radiotherapy).
“The beneficial impact of adjuvant radiotherapy on survival in patients with prostate cancer with lymph node invasion can depend on individualized tumor characteristics,” Dr. Abdollah and his colleagues wrote (J. Clin. Onc. 2014 Sept. 22;[doi:10.1200/JCO.2014.58.1058]).
Those not expected to benefit could be spared unnecessary treatment and adverse effects associated with radiotherapy, they said. Previous studies have suggested that two positive lymph nodes might serve as a cutoff for indicating radiotherapy, the researchers noted, while this study added the additional subgroup of patients with three or four positive nodes. Dr. Abdollah and colleagues noted as limitations of their study its nonrandomized, retrospective design, and the fact that the decision to initiate radiotherapy was left to the clinical judgment of the treating physician, allowing for the possibility of selection bias. None of the researchers declared conflicts of interest.