Insulin-like Growth Factor-1, Insulin-like Growth Factor Binding Protein-3, and Body Mass Index: Clinical Correlates of Prostate Volume Among Black Men

Objectives: To examine the relationship between insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and body mass index and prostate volume, as a surrogate marker for benign prostatic hyperplasia, in a community-based sample of black men. Epidemiologic studies examining the role of IGF-1 and IGFBP-3 suggest that increased levels of serum IGF-1 and decreased levels of serum IGFBP-3 are associated with an increased risk of prostate cancer. Few studies have examined these factors with respect to benign prostatic hyperplasia, and these have been limited to white men.

Methods: The study population consisted of a sample of 364 black men, 40 to 79 years of age, residing in Genesee County, Michigan. Men with prostate cancer or prior prostate surgery were excluded. All subjects completed a clinical examination, which included a complete urologic examination with transrectal ultrasonography, anthropometric measurements, and serum assays for IGF-1 and IGFBP-3.

Results: Multivariable regression models demonstrated that prostate volume increased with increasing age (P <0.0001) and body mass index (P = 0.03). IGFBP-3 rather than IGF-1 was positively associated with increasing prostate volume (P = 0.003).

Conclusions: This is the largest study describing the relationships between IGF-1, IGFBP-3, and body mass index and prostate volume, and the only study in black men. Although earlier studies demonstrated an association between IGF-1 and prostate cancer risk, our findings indicate that IGFBP-3 is more relevant for prostate enlargement, suggesting that IGF-1 and IGFBP-3 may play different pathophysiologic roles in benign and malignant prostatic conditions.