Serum testosterone levels, testis volume, and the risk of prostate cancer: are these factors related?

Objective: Inconclusive results have been published in the literature regarding the relationship between free and total serum testosterone levels and prostate cancer. We investigated the relationship between total and free serum testosterone levels, testes volume, and prostate cancer in our patient population. Material and methods: Total and free serum testosterone levels and serum PSA levels were recorded for 102 consecutive patients. All of the patients underwent transrectal ultrasonography-guided prostate biopsy due to an abnormal digital rectal examination finding and/or a serum PSA level of >4.0 ng/mL. All of the transrectal and testis US examinations and prostate biopsies were performed by the same radiologist. The testis length, width, and height were measured from transverse and longitudinal gray scale images, and the testis volume was calculated. Results: Prostate cancer was detected in 32 of 102 patients (31.3%) who underwent prostate biopsy (prostate cancer group). The remaining patients had benign histopathological findings (prostate cancer-free group). The prostate cancer and benign histology groups were compared for age, total and free testosterone, PSA values, and testis volume. The patients with prostate cancer were found to have a higher mean age (p=0.04). There were no significant differences in serum PSA levels, free or total testosterone levels, or testis volumes between the two groups (p>0.05). A binary logistic regression analysis showed that neither free nor total testosterone was a predictor of prostate cancer (p=0.315 and p=0.213, respectively). Only age was found to be a significant risk factor for the development of prostate cancer (p=0.02). Conclusion: Our study failed to show a relationship between total or free serum testosterone levels, testis volume, and the risk of prostate cancer. Therefore, monitoring serum testosterone levels for prostate cancer prediction does not appear to add an advantage over PSA screening