Increase in Serum Total IGF-I and Maintenance of Free IGF-I Following Intentional Weight Loss in Pre-menopausal Women at Increased Risk of Breast Cancer
Harvie M.*, 1, Renehan A. G.2, Frystyk J.3, Flyvbjerg A.3, Mercer T.4, Malik R.5, Adams J.5, Cuzick J.6, Howell A.1
Identifiers and Pagination:Year: 2010
First Page: 63
Last Page: 70
Publisher Id: TOOBESJ-2-63
Article History:Received Date: 01/07/2009
Revision Received Date: 05/08/2009
Acceptance Date: 06/08/2009
Electronic publication date: 14/7/2010
Collection year: 2010
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Intentional weight loss may reduce breast cancer risk through lowering levels of circulating free IGF-I but few studies have measured this longitudinally. We determined the effect of weight loss (≥5% body weight) over 12 months, using an energy restriction and exercise programme, on an expanded panel of IGF-related peptides amongst 23 weight losing and 46 weight stable or gaining pre-menopausal women at increased risk of breast cancer, BMI (mean ± SD) 29.2 ± 6.2 kg/m2. Fasting measures of total and free IGF-I (ultra-filtration), and IGFBP-1, -2 and -3, body weight, body fat (DXA), intra-abdominal fat (MRI) were assessed at 6 and 12 months.
After 12 months, women who lost ≥5% of body weight had a significant increase in serum total IGF-I; mean (95% CI difference) 17 (2.3 to 34.0) μg/l, P < 0.05, and IGFBP-2; mean (95% CI ratio) 1.24 (1.06 to 1.46) P < 0.001, compared to weight stable/gaining women. Serum IGFBP-1 tended to increase in weight losers compared to the weight stable/gaining women; mean (95% CI ratio) 1.19 (0.97 to 1.45) P=0.09, whereas IGFBP-3 remained unchanged; mean (95% CI ratio) 1.02 (0.94 to 1.20] P=0.99. Weight loss did not significantly alter serum levels of free IGF-I; mean difference 0.1 (-0.1 to 3.4) μg/l, P=0.21.
Increased serum total IGF-I levels, and maintenance of free IGF-I despite increased concentrations of serum IGFBP-1 and -2 with weight loss, does not suggest intentional weight loss with diet and exercise mediates reduced risk through the circulating IGF-axis.