Hormonal risk factors for endometrial cancer: modification by cigarette smoking (United States)

To evaluate whether smoking modifies the risk of endometrial cancer associated with body mass index (BMI), postmenopausal hormone use, and other hormonal factors.

Using multivariate adjusted models we examined interview data from a population-based case-control study of Wisconsin women (n = 740 cases, n = 2,372 controls).

The relative risk for endometrial cancer associated with current smoking was 0.8 (95% CI: 0.6-1.0) compared to never smokers. No clear dose-response relationship was evident for pack-years smoked. When examined according to smoking status the risk associated with the highest quartile of BMI seemed to be greater among non-smokers (OR = 3.6, 95% CI: 2.4-5.3) than among current smokers (OR = 2.8, 95% CI: 1.4-5.6). Among postmenopausal women the risk associated with current use of postmenopausal hormones appeared to be greater among non-smokers (OR = 3.3, 95% CI: 2.3-4.9) than among current smokers (OR = 2.7. 95% CI: 1.3-5.5). Risk for long-term use (10 or more years) compared with never users was 8.3 (95% CI: 4.6-15.1) among never smokers and 2.5 (95% CI: 0.8-7.9) among current smokers. The risk associated with non-insulin-dependent diabetes was greater among non-smokers (OR = 2.5, 95% CI: 1.7-3.6) than current smokers (OR = 1.1, 95% CI: 0.4-3.1). There was no modifying effect of smoking on the risk associated with parity.

These results suggest that smoking moderates the risk associated with endometrial cancer among women at greatest risk, specifically women who are obese or who use postmenopausal hormones.