6931 Weight Trends and Predictors of Weight Gain in Breast Cancer Survivors

Abstract Disclosure: M.D. Hurtado: None. E. Tama: None. D. Hodge: None. A. Weston: None. S. Fahad: None. K. Ruddy: None. J. Olson: None. F. Coach: None. R. Carter: None. S. D'Andre: None. A. Acosta: Consulting Fee; Self; Amgen Inc. Grant Recipient; Self; Vivus USA, Novo Nordisk. C. Shufelt: None. Background: Breast cancer (BC) is the most common cancer in women. Weight gain after treatment for early-stage BC is associated with a higher risk of recurrence. Excess adiposity is also a major risk factor for cardiovascular disease, the leading cause of non-BC related death in BC survivors. This study aimed to describe weight trends in a large cohort of BC survivors and to identify predictors of weight gain after BC diagnosis. Methods: This was a retrospective study of BC survivors from the prospectively consented Mayo Clinic Breast Cancer Registry, which has enrolled >10,000 patients seen at least once at Mayo Clinic Rochester for a BC diagnosed within the prior year. We extracted data on weights at baseline, and years 1, 4, and 6 after BC diagnosis to generate longitudinal weight trajectory curves on the change from baseline. Weights were either reported by patients in the registry questionnaires or extracted from the electronic health records. We identified BC survivors with weight gain >10% from baseline weight at years 1, 4, and 6. We then conducted univariable logistic regression analyses to identify predictors of >10% weight gain. Variables considered included: demographics, anthropometrics, BC clinical and pathologic characteristics, BRCA 1 and 2 genetic mutation status, and treatment (surgery, neoadjuvant or adjuvant chemotherapy, and/or radiotherapy). Results: We included 4744 BC survivors, mostly white (95%) and non-Hispanic (91%), with a mean age and weight at BC diagnosis of 58 ± 13 years and 76 ± 18 kg. Most patients had clinical stage I (43%) and ER+ and PR+ BC (83% and 76%, respectively). Most patients underwent breast preserving surgery (62%), half received radiation (54%), one third (36%) received systemic chemotherapy, and two thirds (61%) received endocrine therapy. At one year after BC diagnosis the average weight change was negligible compared to baseline (mean difference -0.2 ± 8 kg), but there were small but significant average increases by years 4 and 6 (0.5 ± 9 kg, p=0.002; and 0.8 ± 10 kg, p<0.001; respectively). At years 1, 4, and 6, the percentage of BC survivors gaining >10% of their baseline weight was 10%, 15%, and 18%, respectively. Baseline characteristics associated with >10% weight gain at 6 years included lower baseline weight (p<0.001), younger age at BC diagnosis (p<0.001), more advanced clinical and pathologic BC stage (p=0.008), ER+ and PR+ tumor biology (p=0.02 for both), BRCA2 mutation (p<0.001), mastectomy (compared to breast preserving surgeries, p=0.008), the use of systemic chemotherapy treatment (p<0.001), and the use of endocrine therapy (p=0.03). Conclusion: While most BC survivors do not experience weight gain after survivorship, 1 out 5 may experience excessive weight gain of more than 10%. Baseline anthropometric and BC-related variables are associated with excessive weight gain and could be used as predictors of weight gain in this population. Presentation: 6/3/2024