A population-based cohort study on sun habits and endometrial cancer

Abstract

Background: No large cohort study has examined the risk of endometrial cancer in relation to sun exposure. Methods: A population-based cohort study of 29508 women who answered a questionnaire in 1990-92, of whom 24098 responded to a follow-up enquiry in 2000-02. They were followed for an average of 15.5 years. Results: Among the 17822 postmenopausal women included, 166 cases of endometrial cancer were diagnosed. We used a multivariate Cox regression analysis adjusting for age and other selected demographic variables to determine the risk of endometrial cancer. Women using sun beds >3 times per year reduced their hazard risk (HR) by 40 (0.6, 95 confidence interval (CI) 0.4-0.9) or by 50 when adjusting for body mass index or physical activity (HR 0.5, 95 CI 0.3-0.9), and those women who were sunbathing during summer reduced their risk by 20 (HR 0.8 95 CI 0.5-1.5) compared with women who did not expose themselves to the sun or to artificial sun (i.e., sun beds).Conclusion: Exposure to artificial sun by the use of sun beds >3 times per year was associated with a 40 reduction in the risk of endometrial cancer, probably by improving the vitamin D levels during winter. © 2009 Cancer Research UK All rights reserved.