Does obesity affect the accuracy of prostate‐specific antigen (PSA) for predicting prostate cancer among men undergoing prostate biopsy

Abstract

What's known on the subject? and what does the study add?: As most urologist known, obesity significantly lowers serum PSA levels. So there is some concern about delayed diagnosis of prostate cancer in obese men. In the present study, we found that the accuracy level of PSA for detecting prostate cancer was not significantly different between different obesity levels. A well-designed study adjusting for several factors, e.g. diet, exercise, medication and comorbidity, which may possibly compensate for the associated effects on PSA levels, is needed for confirmation of the present findings. To investigate prostate-specific antigen (PSA) accuracy in detecting prostate cancer according to body mass index (BMI) in Asian men with a PSA level of <30 ng/mL using contemporary multicore (≥ 12) prostate biopsy. We reviewed the records of 3471 patients, whose initial PSA levels were <30 ng/mL, who underwent multicore (≥ 12) transrectal ultrasound-guided prostate biopsy between January 2004 and May 2011. BMI was categorised as performed previously for the Asian population: <23, 23-24.9, 25-29.9, and ≥ 30 kg/m(2) . PSA accuracy for detecting prostate cancer in each BMI group was assessed based on the receiver operating characteristics-derived area under the curve. The mean age and median PSA level were inversely associated with BMI; the median PSA level in each BMI category was 7.84, 7.75, 7.33 and 5.79 ng/mL, respectively (P < 0.001). In all, prostate cancer was detected from biopsy in 1102 (31.7%) patients. The PSA accuracy for predicting prostate cancer in all patients was estimated to be 0.607, and PSA accuracies in each BMI category were 0.638, 0.572, 0.613 and 0.544, respectively; there was no significant difference among the groups in terms of PSA accuracy. The accuracy of PSA in predicting prostate cancer did not change regardless of BMI category in Asian men. However, as patients with higher BMIs had lower PSA levels than those with lower BMIs, it can therefore be suggested that the PSA threshold should be lower in obese men to discriminate between prostate cancer and benign conditions in the real clinical situation.