Background: Weight gain after breast cancer (BC) diagnosis is a well-known phenomenon; however, it is not a universal phenomenon and identification of patients at highest risk for weight gain is needed. This study investigates weight trajectories in early BC patients at 2 years post-primary treatment, examining potential contributing factors such as age, race, and receipt of chemotherapy, anti-HER-2 therapy, and endocrine treatment (ET).
Methods: A single institution cohort of newly diagnosed women age 21 and older with early breast cancer patients (Stage 0-3) were identified by retrospective chart review (diagnosis year 1995 to 2016). Log-binomial regression models for net weight changes at 2 years post-primary treatment including patient demographic, clinical, and treatment characteristics.
Results: The final sample of 625 patients included 29% who were non-White and 37% who were pre-menopausal at diagnosis. Body mass index (BMI) at diagnosis was calculated and found to be normal in 33% (BMI 18 to < 25), overweight in 27% (BMI 25 to < 30), and obese in 40% (BMI 30 and higher). At 2 years, compared to weight at diagnosis, 31% had lost > 2 kg, 34% had stable weight ± 2 kg, and 35% had gained > 2 kg. Factors associated with > 2 kg weight gain were menopausal status (pre-menopausal HR 1.65, 95% CI 1.34-2.04, p < .0001), receiving any chemotherapy (HR 1.36, 95% CI 1.04-1.77), and anthracycline-based chemotherapy followed by ET (HR 1.60, CI 1.01-2.45). Anti-HER-2 therapy and transition from pre- to post-menopausal during the 2-year study period were not significant factors in weight gain. In multivariate analysis, menopausal status remained the only significant variable related to weight gain when adjusted for treatment. For all treatment combinations, pre-menopausal women had significantly more weight gain.
Conclusions and relevance: Weight gain, weight loss, and stable weight in women with early breast cancer vary greatly by treatment plan. However, pre-menopausal patients have the highest risk for weight gain.
Keywords: Breast cancer; Treatment regimens; Weight trajectories.