Plasma levels of IGF-1, IGF-2, and IGFBP-3 in white and African-American men at increased risk of prostate cancer

Objectives. To further investigate the relationship between the plasma leve ls of insulin-like growth factor-1 (IGF-1), insulin-like growth factor-2 (I GF-2), insulin-like growth factor binding protein-3 (IGFBP-3), growth hormo ne, testosterone, and demographic factors, particularly race, within a grou p of men at increased risk of prostate cancer development. Methods. Enzyme-linked immunosorbent assays or an immunosorbent assay was u sed to quantitate the plasma levels of IGF-1, IGF-2, IGFBP-3, growth hormon e, and testosterone. The study group consisted of 169 men (85 African-Ameri can, 84 white) aged 35 to 69 years, with no personal history of prostate ca ncer, but having at least one first-degree relative diagnosed with the dise ase, unless they were African-American. The relationships between the plasm a levels and the categorical covariates were assessed using the nonparametr ic Wilcoxon test and between the continuous variables using Spearman's corr elation coefficient. Results. The mean plasma levels of IGFBP-3 were significantly lower in Afri can-American (2657 ng/mL) than in white (2965 ng/mL) men (P = 0.0062). The plasma levels of IGF-2 were also lower in the African-American (503.5 ng/mL ) than in the white (549.1 ng/mL) men (P = 0.0084). Overall, the IGF-1 plas ma levels correlated positively with the IGF-2, IGFBP-3, and growth hormone levels and the IGF-2 plasma levels correlated negatively with the testoste rone levels. Conclusions. Our results demonstrate that lower plasma levels of IGFBP-3 an d IGF-2 are associated with race in a population of men at increased risk o f developing prostate cancer. The ability of these markers to predict earli er disease onset is currently under investigation. (C) 2001, Elsevier Scien ce Inc.