Insulin-like growth factors, insulin-like growth factor-binding proteins, and endometrial cancer in postmenopausal women: results from a U.S. case-control study.

OBJECTIVE To assess whether circulating insulin-like growth factor-1 (IGF-1), IGF-2, insulin-like growth factor-binding protein-1 (IGFBP-1), or IGFBP-3 were associated with endometrial cancer in postmenopausal women. STUDY DESIGN Between 1987 and 1990, we conducted a case-control study of 405 women with endometrial cancer and 297 matched population-based controls. This analysis included 174 postmenopausal cases and 136 controls. RESULTS In logistic regression models adjusted for potential confounders, higher IGF-1 levels were not positively associated with endometrial cancer: odds ratio (OR) for the highest tertile versus the lowest tertile = 0.63, 95% confidence interval (CI) = 0.30-1.32. Endometrial cancer was inversely associated with IGF-2 (OR for the highest tertile = 0.35, 95% CI = 0.18-0.69) and IGFBP-3 (OR for the highest tertile = 0.40, 95% CI = 0.21-0.77), and not associated with IGFBP-1. CONCLUSION Serum IGF-1, IGF-2, and IGFBP-3, but not IGFBP-1, were inversely associated with endometrial cancer in postmenopausal women. These associations and the potential role of the IGF system in endometrial proliferation and carcinogenesis warrant further research.