Lower breast cancer risk with sun exposure

A STUDY of Canadian women has backed the hypothesis that improved vitamin D levels reduce breast cancer risk.

Researchers assessed the sun exposure of more than 3000 women who developed the cancer compared with a similar number of controls. Women spending > 21 hours per week outdoors had a lower incidence of the cancer, compared with those who spent < 6 hours per week outdoors.

The age-adjusted odds ratio of reduced breast cancer risk associated with time spent outdoors was 0.71 in the teenage years, 0.64 in 20s–30s, 0.74 in the 40s–50s and 0.50 from 60–74 years.

“The results of this large population-based case control study suggest that time spent outdoors and our derived proxy measure of vitamin D from sun are inversely associated with breast cancer risk,” the researchers said. 

Am J Epidemiol 2011, online 9 June