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N26 Repeat prostate biopsies – when and for whom?

      Introduction and Objectives

      The aim of this study was to identify parameters for better prediction of prostate cancer at repeat biopsies and estimate the optimal time for such sets of biopsies.

      Material and Methods

      All patients who had undergone prostate biopsies at single institution since May 2007 to Apr 2008 were involved into study. If previous biopsies for these patients were performed, the pathologist's data base was used. Age, prostate specific antigen (PSA), high grade prostate intraepithelial neoplasia (HG PIN), low grade prostate intraepithelial neoplasia (LG PIN), time between biopsy sets and prostate volume were chosen for evaluation of influence of these parameters on prostate cancer detection rate at repeat biopsies. Descriptive statist, Chi-square test and logistic regression were used for analysis of our data using SPSS 13.0 statistical analysis software for Windows.

      Results

      899 were involved into this study. Overall prostate cancer (PCa) detection rate was 49.27% (443 cases of 899). The PCa detection rate at 1st biopsy was 36.15% (325 of 899), at 2nd – 26.7% (81 of 303), 3rd – 21.7% (25 of 115), 4th – 24.4% (10 of 41), 5th – 9.1% (1 of 11) and 6th – 16.7% (1 of 6). Repeat biopsies had been undergone by 303 pts. and PCa was found in 118 (38.94%) cases. PCa detection rate at repeat biopsies was 26.63% of all cancer cases of our study. Time of 2nd repeat biopsy (<6 vs. 6–12 vs. >12 months) has no influence on PCa detection rate (27.3 vs. 21.6 vs. 31.8% respectively) – Chi-square test 3.055, p = 0.222. Time of all repeat biopsies (<12 vs. 12–24 vs. >24 months) in cases when PCa was detected has also no influence on cancer detection rate (38.2 vs. 42.5 vs. 33.8% respectively) – Chi square test 1.39, p = 0.509. The patient's age, PSA at the time of biopsy, HG PIN, LG PIN, time between biopsy sets have not been used as predictors of PCa detection at repeat biopsies. Logistic regression analysis shows that only prostate volume is a significant independent predictor for cancer detection at repeat prostate biopsies – Exp(B) 0.987, 95% CI 0.968–0.989, p = 0.0001. Significantly different PCa detection rate (52.1 vs. 42.2 vs. 24.8%) compares to prostate volume <40 vs. 40–60 vs. >60 mL (p = 0.001) was also detected using Chi-square test.

      Conclusions

      Time between repeat prostate biopsy sets has no influence on detection of prostate cancer. Prostate volume is a powerful parameter for prediction of prostate cancer at repeat biopsy and it could be used for choosing the time of repeat biopsy.