['The purpose of this study was to determine the fraction of men who would qualify for active surveillance in a population based cohort diagnosed with prostate cancer. In those who qualified and subsequently underwent primary treatment with radical prostatectomy, we assessed the rate of upgrading and up staging.', 'SABOR is a Clinical and Epidemiologic Center of the EDRN (Early Detection Research Network), NCI (National Cancer Institute), with 3,828 men enrolled at the time of review. Of these men 320 were diagnosed with prostate cancer, of whom 281 had sufficient data for review. These 281 cases were reviewed to determine suitability for active surveillance using 2 sets of criteria. Criteria 1 were prostate specific antigen density less than 15%, 2 or fewer cores involved with cancer, Gleason score 6 or less and cancer involving 50% or less of biopsy volume. Criteria 2 were 4 or fewer cores with Gleason 3 + 3 cancer and only 1 core of Gleason 3 + 4 cancer with up to 15% of core involved with Gleason 3 + 4 disease. For those undergoing radical prostatectomy, we examined rates of up staging and upgrading.', 'Of the 281 patients, 187 (67%) qualified for active surveillance under criteria 1 and/or 2. Treatment data were available on 178 patients, and 74 underwent radical prostatectomy. Using the initial biopsy, 14 men (33.1%) who met criteria 1 and 9 (25%) who met criteria 2 were upgraded and/or up staged on final pathological review. By comparison, 38% of those who did not qualify for active surveillance were upgraded and/or up staged.'] Is active Surveillance an Appropriate Management Strategy for a Proportion of Men Diagnosed with Prostate Cancer by Prostate Specific Antigen Testing?