Environmental pollution increases the risk of breast cancer in women after menopause
Living in areas with a higher proportion of green spaces for long periods of time could reduce the risk of contracting the disease in women after menopause. For women before menopause, only living in areas with very high concentrations of PM10 increases the risk of breast cancer.
A team of researchers from the IDIAPJGol followed up 1,054,180 premenopausal women and 744,658 postmenopausal women for an average of 10 years, between 2009 and 2018. The objective of this study was to study the association between air pollution, green spaces and risk of contracting breast cancer both before and after menopause.
Breast cancer is one of the leading causes of morbidity and mortality in women worldwide. As cited in the article published in the journal Environmental Research by the researchers, it is a more frequent disease in postmenopausal women, probably due to a longer exposure to endogenous estrogens, obesity or lack of of physical activity, among other factors. In contrast, breast cancer among premenopausal women has been associated with more aggressive biology and the presence of certain genes.
The team conducted a cohort study based on the general population of Catalonia using prospectively collected data from the Information System for Research in Primary Care (SIDIAP) in Catalonia. In total, data from 1,798,838 women between 17 and 85 years of age were analyzed.
At the level of environmental pollution, the measurements were of polluting particles (PM2.5 and PM10) and nitrogen dioxide (NO2 ). Regarding green spaces, the NVDI (Normalized Difference Vegetation Index) and the percentage of green spaces in the census areas where women resided were used.
During follow-up, 6,126 (0.6%) premenopausal women were diagnosed with breast cancer and 17,858 (2.4%) in the postmenopausal cohort. The mean follow-up time was 5 years for women who developed breast cancer and 10 years for those who did not develop the disease. For premenopausal women, the mean age at the start of the study was 38 years for those women who were diagnosed with breast cancer and 32 years for those who were not. On the other hand, in postmenopausal women the mean age was 62 and 63 years, respectively.
The researchers found that an increase in the concentration of PM2.5, PM10 and NO2 increases the risk of breast cancer breast in postmenopausal women while in premenopausal women only extremely high concentrations of PM10(≥46 μg/m 3) were associated with an increased risk of breast cancer.
NDVI was only associated with a decreased risk of cancer among postmenopausal women who did not change residence during follow-up or who were followed for at least three years.
According to the researchers, “policies to reduce air pollution and increase the availability of green spaces could help reduce the risk of breast cancer.” And they add that “more studies are needed to better understand the details of the potential effect of green spaces on the risk of breast cancer.”
Article reference:
Air pollution and green spaces in relation to breast cancer risk among pre and postmenopausal women: A mega cohort from Catalonia. Isaura Terre-Torras, Martina Recalde, Yesika Díaz, Jeroen de Bont, Matthew Bennett, Maria Aragón, Marta Cirach, Cristina O'Callaghan-Gordo, Mark J. Nieuwenhuijsen, Talita Duarte-Salles
