Obesity and prostate cancer detection: Insights from three national surveys

Background: Previous studies suggest that obesity is associated with higher prostate cancer progression and mortality despite an association with lower prostate cancer incidence. This study aims to better understand these apparently inconsistent relationships among obese men by combining evidence from 3 nationally representative cross-sectional surveys. Methods: We evaluated relationships between obesity and 1) testosterone concentrations in the Third National Health and Nutrition Examination Survey (NHANES III; n = 845); 2) prostate-specific antigen (PSA) in NHANES 2001-2004 (n = 2458); and 3) prostate biopsy rates in the National Health Interview Survey (NHIS 2000; n = 4789) population. Mean testosterone, PSA concentrations, and biopsy rates were computed for Body Mass Index (BMI) categories. Results: Testosterone concentrations were inversely associated with obesity (P-trend <.0001) in NHANES III. In NHANES 2001-2004, obese (BMI >35) versus lean (BMI <25) men were less likely to have PSA concentrations that reached the biopsy threshold of >4 ng/mL (3% vs 8%; P <.0001). Among NHIS participants, all BMI groups had similar rates of PSA testing (P = .24). However, among men who had PSA tests, 11% of men with BMI >30 versus 16% with BMI <25, achieved a PSA threshold of 4 ng/mL; P = .01. Furthermore, biopsy rates were lower among men with BMI >30 versus BMI <25 in NHIS participants (4.6% vs 5.8%; P = .05). Conclusions: Obesity was associated with lower PSA-driven biopsy rates. These data support further studies to test the hypothesis that obesity affects prostate cancer detection independent of prostate cancer risk by decreasing the PSA-driven biopsy rates.