|Age-standardised death rates from Breast cancer by country (per 100,000 inhabitants). (Photo credit: Wikipedia)|
Long-term exposure to air pollution and mammographic density in the Danish Diet, Cancer and Health cohort (15 page pdf, Stephanie Huynh, My von Euler-Chelpin,Ole Raaschou-Nielsen, Ole Hertel, Anne Tjønneland, Elsebeth Lynge, Ilse Vejborg, Zorana J Andersen, Environmental Health, Apr. 1, 2015)
Today we review research in Copenhagen, Denmark that looked at the link between exposure to NO2 from traffic-related air pollution over 10 years and mammographic density (MD) which has clear associations with breast cancer, the leading cause of death among women. Although breast cancer occurs more frequently in industrialized countries and both it and MD are higher in urban areas, a careful analysis revealed no convincing relation between MD and air pollution. As the authors noted, if there is a link with air pollution, it is via another pathway independent of MD.
“ Breast cancer is the most common type of cancer and one of the leading causes of death among women in the western world…Breast cancer incidence is higher in more industrialized countries, as well in urban areas, suggesting, among other factors, a possible relevance of air pollution”
“MD[mammographic density] is increasingly being used as a biomarker of breast cancer risk, as it is one of the strongest risk factors.. women living in urban areas had greater MD than those living in rural areas”
“Women with more than 75% density in the breast have a four to six times greater risk of breast cancer than women with little density, or fatty breasts”
“We found no convincing association between exposure to traffic-related air pollution and MD. Associations were weak and inverse.. if air pollution increases breast cancer risk, it is likely via a pathway that is independent of MD.”