Poster Presentation 2025 National Cancer Survivorship Conference

Predictors of weight gain after breast cancer: findings from a longitudinal population-based study (#124)

Carolyn Ee 1 , Kelly Loffler 2 , Richard Woodman 2 , Huah Shin Ng 2 , Wendy Brown 3 , Bogda Koczwara 2
  1. Western Sydney University, Penrith, NSW, Australia
  2. Flinders University, Adelaide, South Australia, Australia
  3. University of Queensland, Brisbane, Queensland, Australia

Background

Weight gain after breast cancer is common and negatively impacts quality of life, function, and survival. There is a paucity of research on predictors of weight gain in Australian breast cancer survivors. We aimed to identify predictors of weight gain in women diagnosed with breast cancer and  compare weight trajectories of women with and without breast cancer.

Methods

This was a secondary analysis of self-reported weight and relevant predictors from the cohort born 1946-51 from the Australian Longitudinal Study on Women’s Health, a longitudinal population-based survey. Women were surveyed from 1996 – 2019 at approximately three-year intervals. Regression models examined the impact of predictors on weight change from previous reported value.

Results

A total of 13714 participants (baseline mean age 47.6 ± 1.5 years and weight 68.7 ± 14.2 kg) were included with 7956 remaining by 2019. At baseline, 276 had history of breast cancer (48.0 ± 1.4 years, 67.0 ± 14.5kg); 976 subsequently developed breast cancer. There was a general trajectory of weight gain (overall mean change from previous wave 1.2 ± 7.7 kg) in the entire cohort; new breast cancer diagnosis was predictive of additional weight gain (coeff 0.44, 95% CI 0.01-0.87, p=0.046). In a multivariable model, health behaviours (exercise, sitting habits) and health condition/status (depression, self-rated health) were predictive of weight change overall, but interaction terms with breast cancer diagnosis were not significant (all pinteraction>0.05). When including breast cancer diagnoses at baseline, pre-menopausal status at diagnosis predicted weight gain (interaction coeff 2.71, 95% CI 0.07-5.36, p = 0.044).

Conclusions

Weight gain is common in midlife women, associated with established factors; breast cancer has a small additional impact. Premenopausal status at breast cancer diagnosis predicts weight gain. Research into underlying mechanisms of weight gain in the context of menopausal changes is needed to inform development of appropriate interventions.