Under Diagnosis and Over Diagnosis of Prostate Cancer

Abstract

We quantified the rates of over and under diagnosis of prostate cancer in 2 large patient cohorts during the last 15 years. A total of 2,126 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 that met our criteria for over diagnosis (0.5 cm3 or less, confined to the prostate with clear surgical margins and no Gleason pattern 4 or 5) and under diagnosis (nonorgan confined, pathological stage T3 or greater, or positive surgical margins) were examined. The proportion of men with an over diagnosed tumor was 1.3% to 7.1%. The proportion with prostate cancer that was under diagnosed 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 over diagnosis 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 over diagnosed cancer. Under diagnosis of prostate cancer continues to occur more frequently than over diagnosis. Lowering the prostate specific antigen threshold for recommending biopsy to 2.5 ng/ml resulted in a lower rate of under diagnosis and a higher progression-free survival rate.