Abstract
Circulating levels of prostate-specific antigen (PSA) and testosterone are widely used for the detection of prostate cancer prior to prostate biopsy; however, both remain controversial. Effective screening strategies based on quantitative factors could help avoid unnecessary biopsies. Here, we sought to clarify the predictive value of free testosterone (FT) vs total testosterone (TT) in identifying patients likely to have positive biopsies. This study aims to develop a novel model for predicting positive prostate biopsy based on serum androgen levels. This study included 253 Japanese patients who underwent prostate biopsy at our institution. TT and FT, %FT (=FT/TT), age, PSA, prostate volume (PV) and PSA density (PSAD = PSA/PV) were assessed for association with prostate biopsy findings. The following results were obtained. Of 253 patients, 145 (57.3%) had positive biopsies. Compared to the negative biopsy group, the positive biopsy group demonstrated higher age, PSA and PSAD but lower PV, FT and %FT by univariate analysis. Multivariate logistic regression analysis indicated PSA, PSAD and %FT were independent predictors of cancer detection. We developed a predictive model based on PSAD and %FT, for which the area under the curve was significantly greater than that of PSA (0.82 vs 0.66), a well-known predictor. Applying this analysis to the subset of patients with PSA <10 ng/mL yielded similar results. We confirmed the utility of this model in another independent cohort of 88 patients. In conclusion, lower %FT predicted a positive prostate biopsy. We constructed a predictive model based on %FT and PSAD, which are easily obtained prior to biopsy.
Highlights
Definitive diagnosis of prostate cancer depends on histopathological verification
Age, prostate-specific antigen (PSA) and PSAD were significantly higher in the positive biopsy group compared with the negative biopsy group
prostate volume (PV), free testosterone (FT) and %FT were significantly lower in the positive biopsy group compared with the negative biopsy group
Summary
Definitive diagnosis of prostate cancer depends on histopathological verification. Prostate biopsy is the only method for definitive diagnosis of prostate cancer. Prostate cancer is usually suspected on the basis of digital rectal examination (DRE) and/or elevated PSA; DRE findings have poor sensitivity, limited specificity and high inter-observer variability. According to EAU-ESTRO-SIOG guidelines on prostate cancer (version 2016) (Mottet et al 2016), PSA is a better predictor of prostate cancer than either DRE or transrectal ultrasonography (TRUS).
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