Circulating insulin-like growth factor-I and benign prostatic hyperplasia--a prospective study.

OBJECTIVE: The aim of this study was to investigate the role of insulin-like growth factor-I (IGF-I), a strongly mitogenic and anti-apoptotic factor, in the development of benign prostatic hyperplasia (BPH). The bioactivity of IGF-I within tissues depends on circulating levels, as well as on the local production of IGF-I and the presence of IGF-binding proteins (IGFBPs). The IGFBPs regulate the efflux of IGF-I to the extravascular space and the bioavailability of IGF-I within tissues. MATERIAL AND METHODS: Within the Northern Sweden Health and Disease Study, 60 cases of BPH defined by a history of prostate resection were identified, and two controls per case were selected. IGF-I, IGFBP-1, IGFBP-3 and insulin were measured by immuno-radiometric assays in stored plasma samples drawn a mean of 3.2 years before surgery. RESULTS: The risk of BPH increased with increasing quartile levels of IGF-I adjusted for IGFBP-3 (p(trend) = 0.10) up to a relative risk of 2.16 (95% confidence interval 0.83-5.64) for the highest quartile. The risk decreased with increasing levels of IGFBP-1 (p(trend) = 0.10). CONCLUSIONS: Our results suggest that elevated IGF-I bioactivity may stimulate the development of BPH; however, they were not statistically significant and require confirmation from larger studies.