Using PSA, biopsy Gleason score, clinical stage, and the percentage of positive biopsies to identify optimal candidates for prostate-only radiation therapy

Purpose: An identification of prostate cancer patients most likely to benefit from prostate-only radiation was made based upon the pretreatment prostate-specific antigen (PSA), biopsy Gleason score, clinical stage, percentage of positive biopsies, and the 5-year postoperative PSA outcome. Methods: Between 1989 and 2000, 2099 patients underwent radical prostatectomy for clinically localized prostate cancer. The primary end points were pathologic evidence of seminal vesicle invasion 2(SVI), extracapsular extension (ECE) with or without positive surgical margins, and the 5-year postoperative PSA outcome. Results: Pretreatment PSA, biopsy Gleason score, and clinical stage were used to assign patients to low-, intermediate-, and high-risk groups. These risk groups were stratified by the percentage of positive biopsies and the primary pathologic and biochemical outcomes examined. The rates of SVI, ECE with positive margin, and no biochemical evidence of disease (bNED) for low-risk patients with ≤50% positive biopsies were 2%, 7%, and 93%, respectively. Patients with >50% positive biopsies had higher rates of SVI and ECE (5% and 11%, respectively) and 52% bNED (p < 0.0001). For intermediate-risk patients with ≤17% positive biopsies, the rates of SVI, ECE with positive margin, and bNED were 3%, 9%, and 90%, respectively. As the percentage of positive biopsies increased above 17% in intermediate-risk patients, there was a statistically significant increase in SVI and ECE and a significant decrease in bNED. Conclusions: Low-risk patients with ≤50% positive biopsies and intermediate-risk patients with ≤17% positive biopsies had a very low risk of SVI and ECE with positive surgical margins. Given that the presence of SVI and ECE with positive surgical margins was uncommon (<10%) with a ≥90% PSA failure-free survival after radical prostatectomy, these patients may be optimal candidates for radiation therapy directed at the prostate only (prostate gland + 1.5-cm margin).