Repeat prostate biopsies predict location of index cancer in an active surveillance cohort

OBJECTIVE To evaluate the ability of repeat prostate biopsies to determine the location of the index cancer for men on prostate cancer surveillance. PATIENTS AND METHODS Forty-five men on active surveillance had a record of the locations of their positive diagnostic biopsy, repeat surveillance biopsy and index cancer (i.e. largest cancer) from prostatectomy specimens. Logistic regression analysis was used to evaluate the association between two consecutive needle biopsies showing cancer in an identical location and the outcome of finding the index cancer at the same location as the initial diagnostic biopsy. RESULTS Eighteen of 45 (40%) men ultimately had an index cancer at the same location as their diagnostic biopsy. Thirteen men had two consecutive biopsies that showed cancer at the same location each time; nine of these men ultimately had an index cancer at that same location. In multivariable logistic regression analysis of men with at least two biopsies, having two initial consecutive biopsies with the same location increased the odds (odds ratio 5.9; 95% CI 1.1-31, P= 0.037) of having an index cancer at the same location as the initial biopsy in a cohort of men on active surveillance. CONCLUSIONS A substantial proportion of men in an active surveillance cohort who undergo prostatectomy ultimately have evidence of an index cancer at the same location as their initial biopsy. This is more likely to be the case when a repeat biopsy shows evidence of cancer at the same location.