Abstract P6-10-11: Longitudinal comparison of weight change in breast cancer survivors to cancer-free women: a prospective study in women with a familial risk of breast cancer

Background: Although postdiagnosis weight gain has been reported in breast cancer (BC) survivors from the general population, weight gain has not been studied in survivors with a familial BC risk who tend to be younger, treated with chemotherapy and more frequently diagnosed with an estrogen receptor (ER) negative BC. In addition, most studies of weight change in survivors have not included a comparison group of cancer-free women and therefore are unable to distinguish the impact of cancer or related treatment on weight gain versus increasing age. In this study we examine the change in weight among survivors compared to cancer-free women from the same high-risk cohort. Methods: In an ongoing prospective cohort of women at Johns Hopkins with a family history of BC, ovarian cancer, and/or a BRCA1/2 mutation, we identified 303 survivors of incident stage 0-III BC and 552 cancer-free women who were ≥ 20 years at enrollment, completed a baseline questionnaire and at least one follow-up questionnaire within 4 years. Linear and logistic regression was used to estimate change in self-reported weight from baseline to follow-up between survivors and cancer-free women. Survivors were categorized based on time between BC diagnosis and baseline, as well as BC treatment categories. Results: Greater than 60 percent of BC survivors were diagnosed under 50 years, and 22.3% had ER negative tumors. Neither weight nor body mass index (BMI) at baseline differed between survivors and cancer-free women; this was irrespective of tumor subtype. Survivors were more likely than cancer-free women to have ever used statins (19.5% in survivors vs. 14.9% in cancer-free women). Average change in weight during follow-up was 2.92 (95% CI 0.92, 4.91) pounds greater in survivors compared to cancer-free women after adjustment for age, baseline BMI, menopausal status, physical activity, statin use, and enrollment year. The greatest weight gain was observed in survivors diagnosed within 5 years prior to baseline, and treated with chemotherapy and not hormone therapy compared to cancer-free women. This group of survivors was 2.12 (95% CI 1.16, 3.90) times more likely than cancer-free women to have gained at least 11 lbs during follow-up. Further those survivors who had used statins gained significantly more weight compared to cancer-free statin users and non-users with and without cancer (p for interaction = 0.012); this increase in weight gain was largely driven by survivors who had received chemotherapy and statins (p for interaction = 0.008). Conclusion: In this study, BC survivors recently diagnosed and treated with chemotherapy were twice as likely to gain at least 11 lbs, compared to cancer-free women. This amount of weight gain has been linked to an increased risk of heart disease and diabetes in women. Therefore survivors in these categories may benefit from early interventions aimed to reduce weight gain. Intriguingly, we observed a statistically significant interaction for statin use on weight gain in chemotherapy-treated survivors, which may reflect an underlying biological interaction between these agents in BC survivors. Given the prevalence of statin use in this population, this needs to be explored further. Citation Format: Amy L Gross, Sarah A Davidovics, Deborah K Armstrong, Jennifer E Axilbund, Betty J May, Kala Visvanathan. Longitudinal comparison of weight change in breast cancer survivors to cancer-free women: a prospective study in women with a familial risk of breast cancer [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 P6-10-11.