Factors associated with weight gain after breast cancer : results from a community-based survey of Australian women

Purpose: Weight gain after breast cancer is common. The aim of this study was to determine factors associated with weight gain after breast cancer in Australian women. Methods: A cross-sectional online survey was conducted between November 2017 and January 2018. Women living in Australia who self-identified as having breast cancer or ductal carcinoma in-situ were eligible. We created stepwise linear and logistic regression models to evaluate predictors for absolute and clinically significant (≥5%) weight gain respectively. Results: Data from 276 women were analysed. Most were Caucasian and 92% had been diagnosed with Stage 0-III breast cancer. Absolute weight gain was associated with hot flushes, being in the menopausal transition at diagnosis, being less physically active than at diagnosis, lower eating self-efficacy when watching television or using a computer, and higher self-efficacy when anxious or nervous (F-ratio = 3.26, R²-adjusted = 0.16, p <.001). Clinically significant weight gain was associated with tamoxifen use (OR 2.7), being less physically active than at diagnosis (OR 3.1), and lower eating self-efficacy when watching television or using a computer (OR 0.82) (Chi-square 64.94, df = 16, p <.001). Weight gain was not associated with chemotherapy, radiotherapy, aromatase inhibitor use, number of lymph nodes removed, or body mass index at diagnosis. Conclusions: Interventions to prevent weight gain after breast cancer, particularly aiming to maintain physical activity, should be targeted at women receiving tamoxifen. The role of eating self-efficacy, especially attentive eating, in managing weight after breast cancer should be explored.