Racial variation in insulin-like growth factor-1 and binding protein-3 concentrations in middle-aged men

Cancer Epidemiol Biomarkers Prev. 1999 Dec;8(12):1107-10.

Abstract

African-American men have the highest and Asian-American men have the lowest prostate cancer incidence rates in the United States; internationally, rates for the Asian continent are among the lowest. Higher insulin-like growth factor (IGF)-1, which participates in the control of cellular growth and differentiation and is modulated by IGF-binding protein-3 (IGFBP-3), was associated with an increased prostate cancer risk in three recent studies. We, therefore, investigated whether plasma levels of IGF-1 and IGFBP-3 vary by race in United States men selected from among members of the Health Professionals Follow-up Study who were 47-78 years old in 1993-1995 when they provided blood (n = 18,000). All of the men who described their major ancestry as African American (n = 63) and a random sample of 75 Asians and 75 Caucasians were invited to provide a second blood sample in 1997, of whom 42, 52, and 55, respectively, did so. IGF-1 and IGFBP-3 concentrations were determined by ELISA. We used nonparametric methods to assess racial variation in age-adjusted levels. Caucasians had the highest median IGF-1 level (224 ng/ml), followed by Asians (208 ng/ml) and African Americans (205 ng/ml). Median IGFBP-3 concentration was similar between Caucasians and Asians but was more than 13% lower in African Americans. Median molar IGF-1:IGFBP-3 ratio was greatest in Caucasians and lowest in Asians. The lower IGF-1 blood levels relative to IGFBP-3 levels among Asian men are consistent with their lower prostate cancer incidence. Although differences in circulating IGF-1 do not seem to account for the greater prostate cancer risk among African-American men, their absolute lower levels of IGFBP-3 may be contributory.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • African Continental Ancestry Group / genetics*
  • Age Distribution
  • Aged
  • Asian Continental Ancestry Group / genetics*
  • European Continental Ancestry Group / genetics*
  • Follow-Up Studies
  • Genetic Heterogeneity
  • Genetic Predisposition to Disease / genetics*
  • Humans
  • Incidence
  • Insulin-Like Growth Factor Binding Protein 3 / blood*
  • Insulin-Like Growth Factor I / metabolism*
  • Male
  • Middle Aged
  • Prostatic Neoplasms / epidemiology*
  • Prostatic Neoplasms / genetics*
  • Risk Factors
  • Statistics, Nonparametric
  • Surveys and Questionnaires
  • United States / epidemiology

Substances

  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor I