Equivalent 5-year bned in select prostate cancer patients managed with surgery or radiation therapy despite exclusion of the seminal vesicles from the CTV

Purpose: Prostate Specific Antigen (PSA) failure free survival was determined for select prostate cancer patients managed definitively with external beam radiation therapy to the prostate only or radical retropubic prostatectomy. Methods and Materials: A logistic regression multivariable analysis evaluating the variables of PSA, biopsy Gleason score, and clinical stage was used to evaluate the endpoint of pathologic seminal vesicle invasion (SVI) in 749 consecutive prostate cancer patients managed with a radical retropubic prostatectomy. In a subgroup of 332 surgically and 197 radiation managed patients who did not have the clinical predictors of SVI, PSA failure free survival (bNED) was determined. Comparisons were made using the log rank test between surgically and radiation managed patients in this subgroup. In this subgroup, radiation managed patients were treated to a median dose of 66 Gy (66-70 Gy) to the prostate only. Results: The pretreatment PSA (>10 ng/ml), biopsy Gleason score (≥7), and clinical stage (T2b, 2c, or 3) were found to be significant independent predictors (p<0.001) of SVI. Only 2% of patients without any of these factors had SVI and 17% had extracapsular extension (15% microscopic; 2% macroscopic). In this subgroup the 5-year bNED rates were equivalent [84 vs. 89% (p = 0.67)] for surgically and radiation managed patients, respectively. Conclusions: Conventional dose external beam radiation therapy directed at the prostate alone resulted in 5-year bNED rates equivalent to surgery on retrospective comparison in patients with clinical stage T1,2a, PSA ≤ 10 ng/ml, and biopsy Gleason ≤ 6 prostate cancer.