Is interval from an initial biopsy a significant predictor of prostate cancer at repeat biopsies?

BACKGROUND: Currently, there are no clear criteria for indicating repeat biopsies in patients with negative results at an initial biopsy of the prostate. The aim of the present study is to determine the clinical and pathological parameters which predict prostate cancer at repeat biopsies with special attention to the interval between biopsies in addition to prostate specific antigen (PSA) and its derivatives. METHODS: We reviewed 100 patients who underwent an initial biopsy that proved negative for prostate cancer and required repeat biopsies between November 1996 and November 2003. Clinical parameters such as age, PSA and its derivatives, interval between biopsies, number of cores taken and initial biopsy histology were analyzed. RESULTS: In total, 31 patients (31.0%) were found to have prostate cancer, 18 (25.7%) of 70 patients by the second biopsy and 13 (46.4%) of 28 patients by the third biopsy. Two patients underwent the fourth biopsy, which revealed no prostate cancer. The patients with a positive biopsy had a significantly longer interval between the biopsies than the patients with a negative biopsy (P=0.0036). Furthermore, in both univariate and multivariate logistic regression analysis, only the interval between the biopsies proved to be an independent predictor of positive results at repeat biopsies (P=0.0094 and 0.0019). CONCLUSIONS: Only the biopsy interval was a significant predictor of prostate cancer at repeat biopsies in both univariate and multivariate analysis.