P4-12-06: Risk Factors for Relative Weight Gain >10% in Breast Cancer Survivors: Findings from the SU.VI.MAX Cohort

Purpose: Since extreme weight gain (EWG, defined as weight gain > 10% of baseline body weight) raises risk for recurrence among breast cancer survivors (Caan et al. AACR 2011) we undertook this study to identify risk factors for EWG after breast cancer. Methods: We screened the database of the SU.VI.MAX trial (13017 pts randomized between low-dose antioxidants and placebo, Arch Int Med 2004) to retrieve women with confirmed breast cancer occurring after inclusion, and post-cancer follow-up. The following data were collected at inclusion and during the study: anthropometric measurements, physical activity, tobacco and alcohol consumption, level of instruction and socio-economic status, current medications. Unlike other breast cancer survivor studies, data have been collected prospectively before breast cancer diagnosis. Data management and data analysis were performed using SAS software 9.1.3. We also screened questionnaires and medical reports to collect data that were not recorded in the study database: type of adjuvant therapy (chemo-and hormone therapy), use of vitamins and dietary supplements, concomitant medications (such as antidepressants, lipid lowering agents, thyroid hormones or anti-thyroid drugs), previous use of HRT, and whether patients were following a diet plan after breast cancer or no. Results: We identified 176 pts with breast cancer included since 1994 in the SU.VI.MAX 8-year Cohort Study. Among them, 25% (n=44) had weight gain >10% of baseline. The only variable significantly correlated with EWG was age at breast cancer diagnosis. Other differences, in particular level of physical activity or anthropometric measurements, did not reach statistical significance. No significant differences were seen between patients with EWG and others regarding the use of adjuvant chemotherapy (34 v 28%), aromatase inhibitors (18 v 22%), or tamoxifen (25 v 21%), previous HRT use (44 v 50%) or concomitant drugs including thyroid hormones (20 v 17%). A minority of patients was following a diet (16 v 17%) but consumption of vitamins or dietary supplements was slightly higher in patients without EWG (35 v 50%). Discussion: Weight gain after breast cancer is a well-known phenomenon affecting at various levels half of breast cancer survivors. Most recent studies suggest that patients with EWG could have an increased recurrence rate. Risk factors for weight gain are still matter of debate but the role of adjuvant chemotherapy is widely admitted. Our results however indicate that adjuvant therapy does not seem to be a major risk factor for EWG. Furthermore, lifestyle and diet do not seem to markedly affect the risk of EWG. The only significant difference observed in our study is age at diagnosis, suggesting that treatment-induced amenorrhea could play a role in some patients. Although identification of women at risk remains difficult, thus precluding a large proportion of this population from tertiary prevention, younger women seem to deserve particular attention. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-12-06.