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 5 alpha-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/m2. 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.