Insulin-like Growth Factor-1, Insulin-like Growth Factor Binding Protein-3 and the Incidence of Malignant Neoplasms in a Nested Case-Control Study

Abstract

Insulin-like growth factor (IGF)-1 is a potent mitogen, but IGF binding protein (IGFBP)-3 inhibits IGF1. To elucidate the relationship between both IGF1 and IGFBP and the risk of tumorigenesis, the association between IGF1 and IGFBP3 serum levels and of malignant tumor incidence was investigated in a prospective case-control study nested in the Japan Collaborative Cohort Study. A baseline survey was started in 1988-1990, 110,585 subjects were enrolled, and 35% of participants donated blood samples. Those who had been diagnosed with malignant tumors by 1997 were considered cases. The analysis involved 1,349 cases and 4,012 controls. Conditional logistic regression was used to estimate ORs for cancer incidence associated with IGF-related molecules. After controlling for alcohol intake, body mass index (BMI), and smoking, participants with high total-IGFBP3 and free-IGFBP3, which is estimated by the molar difference of (IGFBP3 - IGF1), had a risk of future neoplasms (P _trend = 0.014 and 0.009, respectively), but those with IGF1 did not. People in the second to fifth quintiles had a lower risk than those in the first quintile (ORs 0.676-0.736 and 0.657-0.870, respectively). Limiting subjects to those followed for 3 years weakened the negative associations of total- and free-IGFBP3, whereas a positive relationship of free-IGF1, which was estimated by the molar ratio of IGF1/IGFBP3, was seen (P _trend = 0.004, 0.002, and 0.013, respectively). After controlling for alcohol intake, smoking, BMI, and diabetes mellitus, the results were confirmed. These findings suggest that serum IGF1 and IGFBP3 are related to future risk of malignant neoplasms.