Prostate cancers diagnosed at repeat biopsy are smaller and less likely to be high grade.

PURPOSE: We investigated whether prostate cancer diagnosed on initial prostate biopsy had worse pathological outcomes compared to that diagnosed on repeat prostate biopsy.
MATERIALS AND METHODS: We reviewed 905 newly diagnosed prostate cancer cases from 2000 to 2007. Patients were stratified by the number of previous biopsies, including the initial biopsy in 690, and 1 and 2 or greater negative previous biopsies in 142 and 73, respectively. We analyzed Gleason sum, number of cores taken, percent of positive cores and bilaterality of prostate cancer. Clinically insignificant cancers were defined according to prostate specific antigen density 0.4 ng/ml or less, 3 or fewer positive cores, 50% or less of maximum cancer in any core and Gleason sum 6 or less.
RESULTS: Prostate cancer was diagnosed in 57%, 23% and 21% of cases in the initial, and 1 and 2 or greater negative previous biopsies groups, respectively. Initial prostate biopsy showed a higher number and percent of positive cores, and the maximum percent of prostate cancer involved in a core. However, the Gleason pattern distribution differed significantly in the 3 groups with the highest percent (14%) of Gleason sum 8 or greater in the subset with 2 or greater negative previous biopsies (p <0.01). On multivariate analysis accounting for prostate specific antigen, digital rectal examination, age and biopsy schema the number of previous biopsies was an independent predictor of the number and percent of positive cores, maximum prostate cancer involved in a core, and bilaterality (p <0.01). Only prostate specific antigen, digital rectal examination and age but not the number of previous biopsies independently predicted Gleason sum (p <0.01).
CONCLUSIONS: Prostate cancer diagnosed on initial prostate biopsy had higher volume. However, there were a significant number of high grade prostate cancers detected on the third or greater prostate biopsy, underscoring the importance of repeat prostate biopsy in the setting of increased or increasing prostate specific antigen despite negative previous prostate biopsy.