The impact of obesity on the predictive accuracy of PSA in men undergoing prostate biopsy

Obese men have been reported to have lower serum PSA values relative to normal-weight men in population-based studies, screening cohorts, and in men with prostate cancer (CaP) treated with surgery. There are concerns that PSA may be less accurate in detecting prostate cancer in men with increased body mass index (BMI). We determine whether the diagnostic potential of PSA is negatively influenced by obesity by comparing its operating characteristics across BMI categories among men undergoing prostate biopsy.

Demographic, clinical, and histopathological data on 917 men who underwent trans-rectal ultrasound-guided prostate needle biopsy from 2002 to 2010 at a University hospital in Italy were used in the study. Men were categorized for BMI as follows: <25 kg/m(2) (normal weight), 25-29.9 kg/m(2) (overweight), and ≥ 30 kg/m(2) (obese). Receiver operator characteristics (ROC) curves were used to assess PSA accuracy for predicting prostate cancer overall and then stratified according to digital rectal examination (DRE) findings using the area under the ROC curve (AUC).

The obesity rate of the study cohort was 21 %. There was no statistically significant difference in the overall AUCs of PSA for predicting CaP among normal-weight (AUC = 0.56), overweight (AUC = 0.60), and obese men (AUC = 0.60; p = 0.68) in either DRE-positive or negative men.

In a cohort of Italian men undergoing prostate biopsy, the performance accuracy of PSA as a predictor of CaP is not significantly altered by BMI. Obesity does not negatively impact the overall ability of PSA to discriminate between CaP and benign conditions.