Pathological outcomes in men with low risk and very low risk prostate cancer: implications on the practice of active surveillance.

PURPOSE: We assessed oncologic outcomes at surgery in men with low risk and very low risk prostate cancer who were candidates for active surveillance.
MATERIALS AND METHODS: In a prospectively collected institutional database, we identified 7,486 subjects eligible for active surveillance who underwent radical retropubic prostatectomy. Candidates were designated as being at low risk (stage T1c/T2a, prostate specific antigen 10 ng/ml or less, and Gleason score 6 or less) or very low risk (stage T1c, prostate specific antigen density 0.15 or less, Gleason score 6 or less, 2 or fewer positive biopsy cores, 50% or less cancer involvement per core) based on preoperative data. Adverse findings were Gleason score upgrade (score 7 or greater) and nonorgan confined cancer on surgical pathology. The relative risk of adverse findings in men at low risk with very low risk disease was evaluated in a multivariate model using Poisson regression.
RESULTS: A total of 7,333 subjects met the criteria for low risk disease and 153 had very low risk disease. The proportion of subjects at low risk found to have Gleason score upgrade or nonorgan confined cancer on final pathology was 21.8% and 23.1%, respectively. Corresponding values in those at very low risk were 13.1% and 8.5%, respectively. After adjusting for age, race, year of surgery, body mass index, and prostate specific antigen at diagnosis, the relative risk of Gleason score upgrade in men with low risk vs very low risk disease was 1.89 (95% CI 1.21-2.95). The relative risk of nonorgan confined cancer was 2.06 (95% CI 1.19-3.57).
CONCLUSIONS: Men with very low risk prostate cancer were at significantly lower risk for adverse findings at surgery compared to those with low risk disease. These data support the stratification of low risk cancer when selecting and counseling men who may be appropriate for active surveillance.