Presumably, body weight is a modifiable risk factor, which accounts for a substantial proportion of endometrial cases worldwide. A study conducted among European countries estimated that between 26% and 47% of endometrial cancer cases can be attributed to overweight and obesity. The same group conducted a meta-analysis of 12 studies (5 cohort and 7 case-control), which examined the relationship between obesity and endometrial cancer. Eleven of the 12 studies concluded that there is a positive association between endometrial cancer and excess weight.
RRs associated with obesity range from 2 to 10. Some studies show that upper-body and central weight confer a higher risk than peripheral body weight, even after consideration of BMI.[62,63,64] However, other studies have failed to confirm such an association. Several studies have observed a stronger association between endometrial cancer and obesity near the time of diagnosis compared with obesity earlier in life.[65,66,67,68]
Endometrial cancer primarily affects postmenopausal women, with a median age at diagnosis of 60 years.
Women with inherited conditions such as Lynch syndrome, Cowden syndrome, and polycystic ovary syndrome have an increased risk of endometrial cancer. (Refer to the PDQ summaries on Genetics of Breast and Ovarian Cancer and Genetics of Colorectal Cancer for more information.)
Interventions of Unproven or Disproven Effect on Risk
While it is known that obesity is associated with increased endometrial cancer risk, only one study examines the potential benefit of intentional weight loss. In the Iowa Women's Health Study of 21,707 postmenopausal women, participants completed a self-report questionnaire, about intentional weight loss between ages 18 and 39 years, between ages 40 and 54 years, and after age 55 years. Multivariate models adjusting for age, BMI, and BMI2 found no association between endometrial cancer incidence and intentional weight loss of at least 20 lbs (RR = 0.93; 95% CI, 0.60-1.44). The obvious limitation of this study is the reliance on retrospective self-reported data.
Fruits, vegetables, and vitamins
The association between dietary factors, particularly fruit and vegetable intake, and endometrial cancer has been evaluated primarily in case-control studies. A systematic review of the evidence was undertaken as part of the World Cancer Research Fund's Food, Nutrition, Physical Activity and Cancer: A Global Perspective (2006) report. A pooled OR from ten case-control studies for high versus low vegetable intake was 0.71 (95% CI, 0.55-0.91). This association was similar to that reported previously in a report for the International Agency for Research on Cancer, which was based on results from five case-control studies. Neither report observed evidence of an association between fruit intake and endometrial cancer.