Effect of Obesity on Prostate-Specific Antigen, Prostate Volume, and International Prostate Symptom Score in Patients with Benign Prostatic Hyperplasia

PURPOSE We examined the correlation between body mass index (BMI) as a marker of obesity and prostate-specific antigen (PSA), prostate volume (PV), and International Prostate Symptom Score (IPSS) in patients with benign prostatic hyperplasia (BPH). MATERIALS AND METHODS From January 2008 to December 2008, we examined 258 patients diagnosed with BPH. Patients taking 5α-reductase inhibitors or those diagnosed with prostate cancer were excluded from this study. BPH was defined as PV≥25 ml and IPSS≥8. BMI (kg/m(2)) was categorized into 4 groups as follows: BMI<18.5 (underweight), BMI 18.5-23.0 (normal), BMI 23.0-27.5 (overweight), and BMI>27.5 (obese). The relationships between PSA, PV, IPSS, and BMI were analyzed by correlation analysis and one-way ANOVA. RESULTS The mean age of the patients was 65.19±9.13 years and their mean BMI was 23.7±4.4 kg/m(2). The mean PSA values of each BMI group were as follows: 3.42±1.53, 3.07±1.88, 2.74±1.75, and 2.60±1.44 ng/ml. The PSA value was lowest in the obese group. The correlation analysis showed a negative correlation between BMI and PSA (Pearson's correlation coefficient=-0.142, p=0.023) and positive correlations between BMI and PV (Pearson's correlation coefficient=0.32, p=0.001) and IPSS (Pearson's correlation coefficient=0.470, p=0.02). These correlations were also confirmed by one-way ANOVA. CONCLUSIONS Patients with an elevated BMI tended to have lower PSA values, larger PVs, and a higher IPSS. We suggest that weight loss could be helpful for BPH symptom relief as well as for detection of coexisting prostate cancer in BPH patients.