Colorectal cancer and solar radiation

It has been suggested that sunlight might have a role in the prevention of colorectal cancer via a mechanism involving vitamin D. We used data from nine population-based cancer registries in the United States to analyze incidence rates for colon and rectal cancer during 1973–84 as a function of regional variation in the levels of available solar radiation. Data were restricted to include only those persons born and diagnosed in the same state. Incidence rates of colon and rectal cancer among men tended to increase with decreasing levels of solar radiation. Compared to rates in New Mexico and Utah, for example, rates in the Detroit area (MI), Connecticut, and western Washington were 50 percent to 80 percent higher. Among women, colon cancer rates showed a similar trend, though of smaller magnitude; rates of rectal cancer among women did not vary in relation to levels of available solar radiation.Dr Emerson, at the time of this research, was with Dr Weiss at the Department of Epidemiology, University of Washington, School of Public Health and Community Medicine, Seattle, WA and the Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA. Address correspondence to Dr Emerson at her current address: Arizona Cancer Center, Room 2942, University of Arizona, Tucson, AZ 85724, USA. This research was supported in part by Grant No. 1-R35-CA39779 and Grant No. 5-T32-CA09168-13 from the National Cancer Institute.