Correlation between body mass index and prostate volume in benign prostatic hyperplasia patients undergoing holmium enucleation of the prostate surgery

Background: Benign prostatic obstruction (BPO) due to benign prostatic hyperplasia (BPH) is a leading cause of morbidity in men over the age of 40. This study examined whether there was an association between body mass index (BMI) and pre-operative prostate volume and whether expression of two genes, alpha-2-macroglobulin (A2M) and transforming growth factor beta 3 (TGFB3), was correlated with BMI, pre-operative prostate volume, and age at surgery.

Methods: Medical records of patients who underwent holmium enucleation of the prostate surgery for treatment of BPO were retrospectively reviewed. Surgical specimens were obtained from formalin-fixed paraffin-embedded blocks, and expression of the targeted genes was quantified using a real time PCR approach. Linear regression analysis was performed to assess association between BMI and prostate volume adjusting for demographic characteristics and co-morbidity. Spearman's correlation was used to examine whether gene expression was correlated with BMI, prostate volume, and age at surgery.

Results: A total of 278 patients were identified, including 62.9% European Americans (n = 175) and 27.7% Hispanic Americans (n = 77). BMI was significantly correlated with prostate volume (Spearman's rho = 0.123, P = 0.045). In linear regression analysis, BMI was positively associated with prostate volume (β = 0.01, P = 0.004), while hyperlipidemia was negatively associated with prostate volume (β = -0.08, P = 0.02). A trend for a positive association was also observed for diabetes (β = 0.07, P = 0.099). In the race/ethnicity stratified analysis, age at surgery showed a trend for significantly positive association with prostate volume in European Americans (β = 0.005, P = 0.08), but not in Hispanic Americans. Expression of the A2M gene in the stroma was negatively correlated with age at surgery (P = 0.006). A2M expression in the gland was positively correlated with prostate volume among older men (Age ≥ 70, P = 0.01) and overweight men (BMI 25-30, P = 0.04). TGFB3 expression in the gland was positively correlated with BMI (P = 0.007) among older men.

Conclusions: This study demonstrated the positive correlation between BMI and prostate volume. Expression of TGFB3 and A2M was correlated with BMI, prostate volume, and age at surgery.