Abstract P1-09-25: Determinants of weight gain after breast cancer diagnosis: Results from the prospective SU.VI.MAX cohort
Authors: Zelek Laurent , Szabo Fabien , Hercberg Serge , Galan Pilar , Touvier Mathilde 
Published: May 2015

Abstract
PURPOSE To identify correlations between lifestyle related risk factors and weight gain after breast cancer.
MATERIAL AND METHODS The SU.VI.MAX randomized trial was initially designed to assess the effect of a daily antioxidant supplementation on the incidence of cardiovascular disease and cancer. A total of 13,017 subjects were enrolled in 1994–1995. Health events occurring during the follow-up (1994-2007) were self-reported by participants. Pathological reports were used to extract cancer characteristics Anthropometric measurements were taken one year after inclusion in the study and repeated every two years during follow-up. Participants were invited to provide a 24-h dietary record every two months.
Among the 258 invasive breast cancers, 169 had complete weight data before and after cancer diagnosis and were used for analysis. When measured weight and height were not available before diagnosis (n=28), self-reported weight and height were used instead of measured data. After cancer diagnosis, all anthropometric data were measured by study nurses. Women with weight gain (WG) ≥5% (moderate WG) were compared to those with WG &lt;5% by multivariate logistic regression, according to the following factors: menopausal status, educational level, physical activity (irregular, &lt;1h equivalent walking/day, ≥1h equivalent walking/day), smoking status, supplementation group of the trial, weight status before diagnosis, chemotherapy, endocrine therapy, tumor size, pN, mitoses and grade, ER and PR status, mean daily energy intake before diagnosis (&lt;,≥ median=1865 Kcal/d). The same analysis was performed to compare women with WG ≥10% (severe WG) to those with WG &lt;10%. We also calculated the difference between weight before diagnosis and weight at the age of 20 ("lifetime weight change") and we tested its association with the risk of moderate or severe WG.
RESULTS Mean age at diagnosis was 54.4 y. Mean duration between pre- and post-diagnosis weight measurements was 5.8 years. Among the 169 women included, 59.8% were post-menopausal at diagnosis and 28.4% were already overweight before cancer diagnosis. 66 women had a WG ≥5% and 25 had a WG ≥10%. Women who practiced more physical activity at baseline were less incline to face moderate WG (OR=0.42 (0.18-0.97), P=0.04). Moderate WG was also directly associated with hormone receptors status. All other studied factors (including treatment type or energy intake) were not associated with the risk of moderate WG. Surprisingly, tumor size was directly associated with the risk of severe WG (mean tumor size = 14.6mm among women with &lt;10% WG versus 20.1mm among women with ≥10% WG, P=0.04). All other studied factors were not associated with the risk of severe WG. Lifetime weight variation was not associated with the risk of moderate or severe WG.
CONCLUSION Physical activity seems to have a protective effect against moderate WG. Severe WG raises risk for recurrence (Caan B, et al. 2012), but since it is also linked with tumor size, we hypothesize that this relation is more complex than a direct causal effect of WG on recurrence risk.
Citation Format: Laurent Zelek, Fabien Szabo, Serge Hercberg, Pilar Galan, Mathilde Touvier. Determinants of weight gain after breast cancer diagnosis: Results from the prospective SU.VI.MAX cohort [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-09-25.