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Prospective Study of IGF-I, IGF-Binding Proteins, and Breast Cancer Risk, in Northern and Southern Sweden
Rudolf Kaaks, Eva Lundin, Jonas Manjer, Sabina Rinaldi, Carine Biessy, Stefan Söderberg, Per Lenner, Lars Janzon, Elio Riboli, Göran Berglund and Göran Hallmans
Cancer Causes & Control
Vol. 13, No. 4 (May, 2002), pp. 307-316
Published by: Springer
Stable URL: http://www.jstor.org/stable/3553847
Page Count: 10
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Objective: To examine the possible relationships of breast cancer risk to prediagnostic plasma levels of insulin; insulin-like growth factor-I (IGF-I); and IGF-binding proteins -1, -2, and -3. Methods: Within two prospective cohorts in Umeȧ and Malmö we measured plasma concentrations of insulin, IGF-I, and IGFBPs for a total of 513 incident breast cancer cases and 987 matched controls. Results: Globally, risk was unassociated with levels of IGF-I, IGFBP-3, or IGF-I adjusted for IGFBP-3. When breaking down the analysis by subgroups of age at blood donation, an increase in risk was observed for increasing levels of IGF-I in women aged 55 or older, in the Umeȧ cohort only (odds ratios of 1.00, 1.73, 1.76, 1.90; ptrend=0.05). This effect weakned, however, when the analysis was restricted to subjects who did not use exogenous hormones for the treatment of menopausal symptoms. Levels of IGF-I and IGFBP-3 were not related to risk in younger women, recruited before age 50, contrary to observations from previous studies. In a subcohort where blood samples had been collected after at least four hours of fasting, breast cancer risk showed no clear associations with levels of insulin, IGFBP-1, or IGFBP-2. Conclusions: Our results do not confirm earlier findings of an association of plasma IGF-I levels with breast cancer risk especially in young women, but suggest a possible association with postmenopausal breast cancer risk, possibly among ERT/HRT users only. Our results do not support the hypothesis that elevated plasma insulin levels, and reduced levels of IGFBP-1 and IGFBP-2, are associated with increased breast cancer risk.
Cancer Causes & Control © 2002 Springer