Aim : The objective of this study was to investigate the association between various adult weight trajectories (stable, gain, continuously overweight, loss), weight cycling (repeated cycles of intentional weight loss followed by regain) and endometrial cancer risk, overall and by subtype.
Methods : We conducted a large population-based case-control study that collected information on height, weight at three time points (1 year prior to diagnosis, at age 20, maximum), intentional weight loss/regain and other exposures from 1,398 women with incident endometrial cancer and 1,539 population controls.
Results : In multivariable logistic regression models, height was not associated with risk, however higher weight and body mass index (BMI) 1 year prior to diagnosis were associated with increased risk of endometrial cancer (odds ratio [OR] per 1 kg/m2 1.10 95% CI 1.09-1.12). Higher BMI at age 20 years was associated with a modest, but significant, increase in risk (OR 1 kg/m2 1.06 95% CI 1.04-1.09). Higher adult weight gain (≥40kgs) and a weight gain/continuously overweight trajectory during adulthood were also associated with increased risk (p<0.001). Independent of current BMI, weight cycling was associated with a 3-fold increased risk of endometrial cancer among women who had ever been obese (OR 2.9 95% CI 1.8-4.7). There was also suggestion of an inverse association between intentional maintained weight loss and risk of endometrial cancer among women who had been obese at least once during adulthood (OR 0.8 95% CI 0.5-1.3). Risk estimates were most pronounced for endometrioid tumours, but were also seen for non-endometrioid tumours.
Conclusion – These findings support the hypothesis that adult weight gain and possibly weight cycling may increase the risk of endometrial cancer, and highlight the importance of maintaining a desirable weight throughout adulthood.