Purpose: We quantified the rates of over and under diagnosis of prostate cancer in 2 large patient cohorts during the last 15 years. Materials and Methods: A total of 2126 men with clinical stage T1c prostate cancer were treated with radical prostatectomy during 1 of the 3 periods 1989 to 1995, 1995 to 2001 and 2001 to 2005. The respective proportions of men with a tumor met our criteria for overdiagnosis (0.5 cm3 or less, confined to prostate with clear surgical margins and no Gleason pattern 4 or 5) and underdiagnosis (nonorgan confined, pathological stage T3 or greater, or positive surgical margins) were examined. Results: The proportion of men with an overdiagnosed tumor was 1.3% to 7.1%. The proportion with prostate cancer that was underdiagnosed was 25% to 30%. An ancillary finding was that decreasing the prostate specific antigen threshold for biopsy from 4.0 to 2.5 ng/ml in the screened population resulted in a lower rate of under diagnosis from 30% to 26%, a higher rate of overdiagnosis from 1.3% to 7.1% and an increase in the 5-year progression-free survival rate from 85% to 92%. Men who were 55 years or younger were significantly more likely to meet our criteria for overdiagnosed cancer. Conclusions: Underdiagnosis of prostate cancer continues to ocur more frequently than overdiagnosis. Lowering the prostate specific antigen thereshold for recommending biopsy to 2.5 ng/ml resulted in a lower rate of underdiagnosis and a higher progression-free survival rate.

Keywords: prostate, prostatic neoplasms, diagnosis, mass screening, prostate-specific antigen