Insulin-like growth factors and liver cancer risk in male smokers.

Background: The liver is the primary source of circulating insulin-like growth factor (IGF)-I, yet the relation between IGFs and liver cancer is uncertain.

Methods: In a case-cohort study within a cohort of 29,133 male smokers we examined associations of serum IGF-I and IGF binding protein (IGFBP)-3 with liver cancer (50 cases).

Results: Nonlinear associations between liver cancer and IGF-I and IGFBP-3 were observed (P=0.04 and P<0.01, respectively), strongest association at lowest levels (odds ratio (OR)=0.2, 95% confidence interval (CI)=0.1-0.7 for 80 vs 30 ng ml(-1) of IGF-I; OR=0.2, 95% CI=0.1-0.6 for 1400 vs 700 ng ml(-1) of IGFBP-3).

Conclusions: Low IGF-I and IGFBP-3 levels in male smokers are associated with increased risk of liver cancer.