Serum insulin-like growth factor I: tumor marker or etiologic factor? A prospective study of prostate cancer among Finnish men

Cancer Res. 2003 Jul 15;63(14):3991-4.


Recent epidemiological studies suggest an association between higher blood levels of insulin-like growth factor I (IGF-I) and increased risk of prostate cancer. We evaluated the association between prediagnostic levels of IGF-I and insulin-like growth factor binding protein 3 (IGFBP-3) and prostate cancer risk in a nested case-control study within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Within the same cohort (using different cases and controls who had sequential serum samples available) we also examined changes in serum IGF-I and IGFBP-3 levels over time by case status. The risk association study included incident prostate cancer cases (n = 100) diagnosed at least 5 years after baseline blood draw (range, 5-12 years; median 9 years) and frequency-matched (4:1) controls. The sequential serum study included all of the prostate cancer cases (n = 21) with prediagnostic (2-3 years before diagnosis) and diagnostic serum available, and pair-matched controls (1:1). An ELISA was used to quantitate serum levels of IGF-I and IGFBP-3 for both studies. The association between IGF-I or IGFBP-3 and prostate cancer risk was assessed using conditional logistic regression, and paired t tests were used to evaluate case-control differences in change in serum analytes over time. We found no significant association between either IGF-I or IGFBP-3 and prostate cancer risk. In a multivariate analysis, we observed an odds ratio of 0.52 (95% confidence interval, 0.23-1.16) for the fourth versus the first quartile of serum IGF-I. Serum IGF-I, but not IGFBP-3, increased significantly over time in cases (18% increase) but not controls (4% decrease; P = 0.02). In contrast to previous reports, we found no evidence to support a causal association between serum IGF-I or IGFBP-3 and the risk of prostate cancer. It is possible that serum IGF-I may be serving as a tumor marker rather than an etiologic factor in prostate cancer.

Publication types

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

MeSH terms

  • Aged
  • Biomarkers, Tumor / blood*
  • Case-Control Studies
  • Humans
  • Insulin-Like Growth Factor Binding Protein 3 / blood
  • Insulin-Like Growth Factor I / metabolism*
  • Male
  • Middle Aged
  • Prospective Studies
  • Prostatic Neoplasms / blood*
  • Randomized Controlled Trials as Topic


  • Biomarkers, Tumor
  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor I