Abstract P4-13-09: The effect of weight change on breast adipose and dense tissue

Abstract

Abstract Background Observational studies indicate that weight gain or loss alters breast cancer risk. Hormonal prevention with tamoxifen or ovarian suppression reduces mammographic breast density, but has no impact on breast adipose tissue.1 The aim of this study was to assess whether change in weight is associated with change in breast density, breast fat or both. Methods 74 premenopausal women aged between 35 and 45 years, with a family history of breast cancer, were recruited from our Family History Clinic. 36 were allocated to a 25% calorie-restricted Mediterranean diet and exercise intervention; a further 38 women were separately recruited into a control group and given written diet and exercise advice only. At baseline and 12 months breast dense and non-dense (largely adipose) components of the breast were measured: area using Cumulus2 and volume using the Manchester ‘stepwedge’ method.3 Visual assessment of percentage density was reported to the nearest 5%.4 We used correlations to relate percentage change in absolute dense and non-dense (area and volume) to percentage change in: weight, total body fat (DXA), intra-abdominal and subcutaneous abdominal fat (MRI), as well as serum total IGF-I. Results At 12 months, 40 (54%) women lost >1.5% body weight, 14 (19%) gained >1.5% and 21 (28%) remained weight stable, <+/−1.5% weight change. There was a range of percentage weight change from −16.3% to +9.8%. There were no significant changes in dense area (r = −0.14 p = 0.29) or volume (r = −0.01 p = 0.97) with weight change. However, both the area and volume of non-dense breast tissue changed significantly in relation to change in body weight (r = 0.52 p < 0.0001 & r = 0.78 p < 0.0001 respectively), total body fat (r = 0.49 p < 0.001 & r = 0.75 p = <0.0001 respectively), intra-abdominal fat (r = 0.45 p < 0.0001 & r = 0.36 p = 0.03 respectively) and subcutaneous abdominal fat (r = 0.55 p < 0.0001 & r = 0.52 p = 0.002 respectively). Visually assessed percentage mammographic density was significantly inversely related to weight (r = −0.27 p = 0.038). Serum total IGF-I was not significantly correlated with breast dense area. (r = −0.21 and p = 0.09). Conclusions These data indicate that dense area and volume remain stable irrespective of change in weight. Non-dense area changes significantly in response to weight change in parallel with total and abdominal fat stores. These observations were performed on relatively small numbers of women and require confirmation in larger series. 1. Cuzick et al J Natl Cancer Inst. 103(9): 744–52, 2011. 2. Boyd NF et al J Natl Cancer Inst. 87(9) 670–675 1995. 3. Diffy et al IWIDM 2006, LNCS 4046 p1-9. In Astley et al (Eds) Springer-Verlag Berlin Heidelberg 2006 4. Brisson J et al. Cancer Epidemiol Biomarkers Prev 2003;12:7288–32. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-13-09.