Weight gain in hormone receptor-positive (HR+) early-stage breast cancer: is it menopausal status or something else?

Purpose: This study investigates weight trajectories in pre- versus postmenopausal breast cancer (BC) survivors diagnosed with hormone receptor-positive tumors, with a specific focus on discerning menopausal status and type of endocrine treatment (ET) as risk factors for weight gain during ET. Methods: We conducted a retrospective review of electronic medical records. Descriptive statistics and Chi-squared and t tests were used to compare pre- and postmenopausal women. Chi-squared tests and ANOVA were used for within-group associations between patient characteristics and weight trajectories. Log-binomial regression models were used to estimate relative risk for weight gain. Results: The final sample was 32% premenopausal (n = 140) and 68% postmenopausal (n = 298). Relative risk (RR) for weight gain during ET was highest in women who were premenopausal (RR = 1.29, 1.03–1.52) and had Stage 3 BC (RR = 2.12, 1.59–2.82), mastectomy (RR = 1.49, 1.19–1.88), axillary node dissection (RR = 1.39, 1.11–1.73), and chemotherapy (RR = 1.80, 1.37–2.36). For each kg of weight gained between BC diagnosis and start of ET, and for each additional year of age, RR of gaining weight during ET decreased (RR = 0.98, 0.97–0.99, and RR = 0.99, 0.98–0.99, respectively). Menopausal status and type of ET were not significant predictors of weight gain. In multivariable analysis, only weight loss between BC diagnosis and start of ET was significant. Conclusion: The association of weight loss prior to ET and subsequent substantial weight gain during ET warrants further investigation.