Premenopausal Levels of Circulating Insulin-Like Growth Factor I and the Risk of Post-Menopausal Breast Cancer: A Population-Based, Nested Case-Control Study

摘要

High levels of circulating IGF-l may be a risk factor for breast cancer. Only one population-based epidemiologic study of IGF-l and breast cancer measured circulating IGF-l in serum drawn prior to diagnosis. For post- menopausal breast cancer cases, no association was found. However, these analyses did not include IGF-l measures from the pre-menopausal period when endogenous IGF-l exposure is naturally higher and, potentially, more predictive of breast cancer risk. This study is a nested case-control analysis of archived serum samples and existing questionnaire data from the CLUE studies. 5,290 women participated in the prospective CLUE studies -- 129 developed a first, incident invasive breast cancer between 1990 and 1998. Cases diagnosed premenopausally will be excluded. One control will be matched to each case on age, menopausal status, age at menopause, follow-up time, date of each blood draw. Samples will be sent to the lab of Dr. Michael Pollack at McGill University. Plasma IGF-l and IGFBP-3 concentrations will be determined by enzyme-linked immunoabsorbent assay (ELISA) . Statistical analyses will: (1) estimate the association between premenopausal IGF-l levels (with and without adjustment for IGFBP-3) on postmenopausal breast cancer risk; and (2) determine whether this association differs from that for postmenopausal IGF-l levels.