The Prognostic Impact of Seminal Vesicle Involvement Found at Prostatectomy and the Effects of Adjuvant Radiation: Data From Southwest Oncology Group 8794

Abstract

From the randomized study Southwest Oncology Group 8794 we evaluated the effect of seminal vesicle involvement on outcomes and whether those patients benefited from post-prostatectomy adjuvant radiation therapy. Southwest Oncology Group study 8794 randomized high risk patients (with seminal vesicle positive disease and/or capsular penetration and/or positive margins) to radiation vs observation after prostatectomy. A total of 431 subjects with pathologically advanced prostate cancer were randomized. Median followup was 12.2 years. Of the patients 139 had seminal vesicle involvement with or without capsular penetration and/or positive margins. Compared to the 286 patients with seminal vesicle negative disease there was poorer 10-year biochemical failure-free survival (33% for seminal vesicle negative and 22% for seminal vesicle positive, p = 0.04), metastasis-free survival (70% and 56%, respectively, p = 0.005) and overall survival (10-year overall survival 74% and 61%, respectively, p = 0.02) for those with seminal vesicle positive disease. Patients with seminal vesicle positive disease who received adjuvant radiation compared to observation realized an improvement in 10-year biochemical failure-free survival from 12% to 36% (p = 0.001), in 10-year overall survival from 51% to 71% (p = 0.08) and in metastasis-free survival from 47% to 66% (p = 0.09), respectively. Although seminal vesicle involvement is a negative prognostic factor, long-term control is possible especially if patients are given adjuvant radiation therapy. This therapy appears to be effective in patients with seminal vesicle involvement.