Under diagnosis and over diagnosis of prostate cancer

Abstract

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 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.

Results: 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.

Conclusions: 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.