UC Irvine

The relationship between testosterone and prostate cancer is both complex and understudied. Impact of testosterone on disease aggressiveness, overall health status, and sexual function are of particular interest in both prostate cancer patients and in aging men. As such, the present study seeks to explore the impact of free testosterone on sexual function in prostate cancer patients (PCa) undergoing radical prostatectomy.

From 2009 to 2019, 783 men with localized PCa were treated with robot-assisted radical prostatectomy (RARP). Total testosterone and sex hormone binding globuin (SHBG) was collected from all patients and free testosterone (cFT) was prospectively calculated. Sensitivity analysis was performed to identify relevant cut-points in age, free testosterone, and sexual function scores. Impact of free testosterone (cFT), age, comorbidity status, and disease characteristics were considered as covariates and linear regression models were generated to predict sexual function.

In sensitivity analysis, men over the age of 60 had significantly lower cFT, higher serum prostate specific antigen (PSA) and prostate weight. Additionally, these men also had a higher proportion with high-risk (GGG 9-10) and high-volume (p-stage T3/T4) disease. After adjusting covariates in linear regression, cFT was an independent predictor of preoperative IIEF-5 scores for men above the age of 60 years (p=0.001, Beta: 0.140, 95% CI: 0.165 – 0.690). In addition, prostate weight was a significant covariate of preoperative IIEF-5 scores for men above 60 years of age (p=0.013, Beta: -0.110, 95% CI: -0.066 – -0.008). cFT appears to be an independent predictor of preoperative sexual function in older men with PCa.

These results highlight the deleterious effects of long-term exposure to low cFT. We emphasize that cFT (over total testosterone) should be systematically checked in all men regardless of age. Furthermore, testosterone replacement therapy should be considered as an early intervention strategy in at-risk patients.