Low serum testosterone but not obesity predicts high gleason score at biopsy diagnosed as prostate cancer in patients with serum PSA lower than 20 ng/ml

Background/Aim: The impact of testosterone or obesity on the pathological grade of prostate cancer remains controversial. Therefore, in this study, we investigated the relationship of serum testosterone and body mass index (BMI) to Gleason score at biopsy. Patients and Methods: This study included 128 Japanese patients diagnosed with prostate cancer from 2000 through 2012 whose serum testosterone level and BMI were measured before treatment. Associations between clinical parameters, including pre-treatment serum testosterone level and BMI, and Gleason score at biopsy were examined. Results: The median serum testosterone and BMI were 434 ng/dl (interquartile range=362-542 ng/dl) and 23.5 kg/m2 (interquartile range=21.7-25.4 kg/m2), respectively. Gleason score at biopsy was <7, 7 and >7 for 58 patients (45.3%), 52 patients (40.6%) and 18 patients (14.1%), respectively. On univariate analysis, positive finding at digital rectal examination (DRE), high prostate-specific antigen level at diagnosis and low serum testosterone level, but not BMI, were correlated with high Gleason score at biopsy. Multivariate analysis identified positive finding at DRE and low serum testosterone level as significant predictors of a high Gleason score at prostate biopsy. By combining these parameters, the predictive ability of a high Gleason score was improved. Conclusion: This study showed that positive finding at DRE and a low pre-treatment serum testosterone level, but not obesity, may be factors predictive of aggressive prostate cancer, indicating the diagnostic value of serum testosterone, as well as DRE findings, in risk assessment.