Abdominal Adiposity and Testosterone Levels in Patients with Localized Prostate Cancer

Objectives: To analyze the relationship between body mass index (BMI), fat tissue distribution, and total testosterone (TT) levels in men with localized prostate cancer (PCa). Methods: Two hundred and thirty-eight patients with either intermediate-risk PCa (60.5%) or high-risk PCa (39.5%) treated by external beam radiotherapy (EBRT), with or without androgen deprivation therapy (ADT), were analyzed. The visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were identified from patient’s radiotherapy planning computed tomography (CT) images. Patients were divided into two groups: the first included patients whose TT levels were hypogonadal; the second included patients whose TT levels were normal. Results: There was a correlation between VAT and BMI (r=0.627). In an univariate model, BMI (p = 0.0174) and VAT (p=0.0228) were both predictive for low TT; age (p=0.579) was not. In a multivariate analysis taking into account the non-linear relationship between a low TT and BMI, BMI was the only predictive factor of a low TT (p=0.0304). An increase in BMI from 15 to 35 kg/m2 was associated with a fairly linear increase in the probability of having a low TT level; an increase in BMI of 5 kg/m2 resulted in an increase in probability of a low TT of 10%. On the other hand, a BMI >35 kg/m2 had a lower probability of a low TT level. Conclusions: There is a non-linear relationship between hypogonadal TT levels and BMI. VAT was not an independent predictor for low TT levels. Our results emphasize the important relationship between low TT and obesity in patients with PCa.