Preoperative Endogenous Testosterone Density Associates with the Risk of Unfavorable Tumor Grade and Predicts Prostate Cancer Progression in Patients with Clinically Localized Disease Treated with Robot-Assisted Radical Prostatectomy

Background: Predicting postoperative recurrence of prostate cancer (PCa) after robot-assisted radical prostatectomy (RARP) remains challenging. Endogenous testosterone density (ETD) has emerged as a potential biomarker, though its exact prognostic value remains underexplored in specific surgical cohorts. To evaluate preoperative ETD, the ratio of endogenous testosterone to prostate volume (PV; mL), as a predictor of both unfavorable tumor grade and disease progression in clinically localized low-grade (ISUP 1) and high-grade (ISUP 4/5) prostate cancer (PCa). Methods: Between November 2014 and December 2019, 186 patients were selected according to the study criteria. Statistical methods evaluated associations of ETD with study endpoints. Results: In the surgical specimen, 63 cases (33.9%) were low grade (ISUP 1) and 123 (66.1%) high grade (ISUP 4/5). Median (IQR) follow-up was 40 (25–50). PCa progression occurred in 48 subjects (25.8%). Patients presenting with increased ETD levels above 10 ng/(mL × dL) were more likely to associate with high-grade cancer in the surgical specimen (OR = 2.098; 95% CI: 1.028–4.124; p = 0.021) than to undergo disease progression (HR 2.278; 95%CI: 1.258–4.124; p = 0.007). Conclusions: Preoperative ETD was an independent parameter for stratifying clinically localized PCa. ETD levels increased according to the risk of unfavorable tumor grade and disease progression.