Aim: Obesity is an established risk factor for endometrial cancer. Associations tend to be stronger for the endometrioid subtype. The role of adult weight change and weight cycling is uncertain. Our study aimed to determine whether there is an association between different adult weight trajectories, weight cycling and risk of endometrial cancer overall, and by subtype.
Methods: We analysed data from the Australian National Endometrial Cancer study, a population-based case-control study that collected self-reported information on height, weight at three time points (age 20, maximum and 1 year prior to diagnosis [recent]), intentional weight loss/regain (weight cycling) from 1398 women with endometrial cancer and 1538 controls. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable logistic regression analysis.
Results: Relative to women who maintained a stable weight during adulthood, greater weight gain after the age of 20 was associated with increased risk of endometrial cancer (OR for gain 40+kg all subtypes 5.3, 95% CI 3.9-7.3; endometrioid 6.5, 95% CI 4.7-9.0). The strongest associations were observed among women who were continually overweight from the age of 20 (all subtypes OR 3.6, 95% CI 2.6-5.0). Weight cycling was associated with increased risk, particularly among women who had ever been obese (OR 2.9 95% CI 1.8-4.7), with ~3-fold risks seen for both endometrioid and non-endometrioid tumour subtypes. Women who had intentionally lost weight and maintained that weight loss were not at increased risk.
Conclusion: These results suggest that higher adult weight gain, and perhaps weight cycling, independently increase the risk of endometrial cancer, however women who lost weight and kept that weight off were not at increased risk.
Keywords: Body mass index; Endometrial cancer; Histologic subtype; Obesity; Weight change; Weight cycling.
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