IGF-I during primiparous pregnancy and maternal risk of breast cancer

Tianhui Chen (1) , Annekatrin Lukanova (1, 2) , Kjell Grankvist (3) , Anne Zeleniuch-Jacquotte (4) , Marianne Wulff (5) , Robert Johansson (6) , Helena Schock (1) , Per Lenner (6) , Goran Hallmans (7) , Goran Wadell (8) , Paolo Toniolo (2, 4) , Eva Lundin (3)

1 Division of Cancer Epidemiology
2 Department of Obstetrics and Gynecology
3 Department of Medical Biosciences
4 Department of Environmental Medicine
5 Department of Clinical Sciences/Obstetrics and Gynecology
6 Department of Radiation Sciences [Umeå]
7 Department of Public Health and Clinical Medicine/Nutritional Research
8 Department of Clinical Microbiology

Previously, we reported that insulin-like growth factor (IGF)-I during early pregnancy is positively associated with maternal risk of breast cancer. To further explore this association, we designed a new study limited to women who donated a blood sample during their first pregnancy ending with childbirth. A case–control study was nested within the Northern Sweden Maternity Cohort in which repository since 1975, serum specimens remaining after early pregnancy screening for infectious diseases had been preserved. Study subjects were selected among women who donated a blood sample during the full-term pregnancy that led to the birth of their first child. Two hundred and forty-four women with invasive breast cancer were eligible. Two controls, matching the index case for age and date at blood donation were selected ( = 453). IGF-I was measured in serum samples on an Immulite 2000 analyzer. Conditional logistic regression was used to estimate odds ratios and 95% confidence intervals. A significant positive association of breast cancer with IGF-I was observed, with OR of 1.73 (95% CI: 1.14–2.63) for the top tertile,  < 0.009. Subgroup analyses did not indicate statistical heterogeneity of the association by ages at sampling and diagnosis or by lag time to cancer diagnosis, although somewhat stronger associations with risk were observed in women ≤age 25 at index pregnancy and for cases diagnosed within 15 years of blood donation. The results of the study add further evidence for an adverse effect of elevated IGF-I concentrations during early reproductive life on risk of breast cancer.

Mots clés: Insulin-like growth factor (IGF)-I; Breast cancer; Pregnancy; Nested case–control study

Tianhui Chen, Annekatrin Lukanova, Kjell Grankvist, Anne Zeleniuch-Jacquotte, Marianne Wulff, et al.. IGF-I during primiparous pregnancy and maternal risk of breast cancer. Breast Cancer Research and Treatment, 2009, 121 (1), pp.169-175. ⟨10.1007/s10549-009-0519-6⟩. ⟨hal-00485066⟩