Racial differences in adipose tissue distribution and risk of aggressive prostate cancer among men undergoing radiotherapy.

BACKGROUND Although elevated body mass index (BMI) has been associated with increased risk of aggressive prostate cancer, the importance of adipose tissue distribution is not well understood. We examined associations between overall and visceral obesity and aggressive prostate cancer risk. Moreover, given racial differences in adipose tissue distribution, we examined whether race modified these associations. METHODS We conducted a cross-sectional analysis of 308 radiotherapy-treated patients with prostate cancer within the Durham VA from 2005 to 2011. Multivariable logistic regression examined the association between BMI categories and tertiles of waist circumference (WC), visceral fat area (VFA), and periprostatic adipose tissue area (PPAT) with high-grade prostate cancer risk (Gleason score ≥7 vs. ≤6). Models stratified by race examined whether these associations differed between black and nonblack men. RESULTS Both elevated BMI (Ptrend = 0.054) and WC (Ptrend = 0.040) were associated with increased high-grade prostate cancer risk, with similar results between races, although the association with BMI was not statistically significant. In contrast, elevated VFA was associated with increased aggressive prostate cancer risk in black men (Ptrend = 0.002) but not nonblack men (Ptrend = 0.831), with a significant interaction between race and VFA (Pinteraction = 0.035). Though similar patterns were observed for PPAT, none was statistically significant. CONCLUSIONS Among men undergoing radiotherapy for prostate cancer, visceral obesity is associated with increased aggressive prostate cancer risk, particularly among black men. If confirmed in future studies, these results suggest that adipose tissue distribution differences may contribute to prostate cancer racial disparity. IMPACT These findings highlight the need to elucidate mechanisms contributing to racial differences in the association between visceral obesity and aggressive prostate cancer.