BACKGROUND - Adult obesity is a well-established risk factor for endometrial cancer. However, little is known about the association of endometrial cancer risk with body size early in life and weight change during adulthood. We investigated whether women with greater early-age body size or with greater weight change during adulthood have an increased risk of endometrial cancer.
METHODS - We analysed data from a population-based case-control study of endometrial cancer conducted between 1997 and 2001 in Shanghai, China. Included in this analysis were 832 endometrial cancer cases aged 30-69 years and 846 population controls. Information on weight and height history from adolescence through adulthood was obtained via structured in-person interviews. A logistic regression model was used to derive odds ratios (ORs) and 95% confidence intervals (CIs) for endometrial cancer in association with adolescent and adult adiposity, as well as adult body weight change. All ORs were adjusted for age, education, menstrual status, duration of menstruation, number of pregnancies, oral contraceptive use, and family history of cancer.
RESULTS - Perceived weights and heights during puberty that were greater than average were associated with a modestly increased risk of cancer. The association for perceived weight was substantially weakened after adjustment for current body mass index (BMI). High BMI at all adult ages significantly predicted endometrial cancer risk, with recent BMI being the strongest predictor. Further analyses disclosed that weight gain during adulthood, particularly during the peri-menopausal period (age 40-50 years), was associated with a significantly elevated risk of endometrial cancer, even among currently non-obese women. Gaining >5 kg between age 40 and 50 was related to ORs of 2.3 (95% CI 1.4-3.9) for women with a BMI<25 kg/m2 and 2.0 (95% CI 1.3-3.0) for women with BMI>or=25 kg/m2.
CONCLUSIONS - Adult weight gain, particularly during the peri-menopausal period, plays a significant role in the development of endometrial cancer risk.