Air pollution increases the risk of breast cancer

Montreal - Known for their effects on lung cancer, air pollutants like airborne particles could also be a risk factor for breast cancer, according to a meta-analysis published in late June in the Environmental Health Perspectives. Researchers from the French National Institute of Health and Medical Research (known from its French acronym as Inserm), the French National Centre for Scientific Research (CNRS) and the University of Grenoble Alpes, France, analyzed studies associating exposure to pollutants atmospheres and the incidence of breast cancer. Although fine particles less than 10 microns (PM10) and 2.5 microns (PM2.5) have been associated with the risk of breast cancer, the effect would be more marked with nitrogen dioxide (NO2), a gas emitted during the combustion of fossil fuels such as those from thermal engines of vehicles and district heating. To measure the effects of nitrogen dioxide, the researchers considered 36 studies involving more than 3.9 million people and 120,000 cases of breast cancer. This allowed them to identify 36 associations between this chemical compound and breast cancer, all reported in women in North America and Europe. By comparison, 27 and 32 associations were found for suspended particles less than 10 and 2.5 microns, respectively. The estimated effect of nitrogen dioxide would be higher in premenopausal women than in postmenopausal women, as well as for hormone-dependent breast cancers, whose tumors express estrogen and progesterone receptors, although all studies have not been able to consider this criterion. Exposure to atmospheric pollutants associated with nitrogen dioxide could be responsible for 1,677 cases of breast cancer, or about 3% of cases diagnosed each year in France, according to the researchers. The observational approaches used in the studies analyzed did not make it possible to distinguish the potential effect of other pollutants such as polycyclic aromatic hydrocarbons, the carcinogenic effect of which has also been established by the International Agency for Research on Cancer. Another epidemiological study published in April also showed an increased risk of breast cancer with prolonged exposure to four air pollutants: polychlorinated biphenyl 153 (PCB), nitrogen dioxide (NO2) and fine particles PM2.5. and PM10. Researchers from the Léon Bérard Centre in the Environmental Cancer Prevention Department (Lyon) also revealed an association between an increased risk of breast cancer and long-term exposure to benzo [a] pyrene (BaP), an atmospheric pollutant classified as endocrine disruptor. It is formed during the incomplete combustion of organic materials such as the burning of plants in the open air, automobile exhaust fumes or cigarette smoke. A risk increased by 20% when women are exposed during the menopausal transition period. Bias to consider Inserm stresses that the meta-analysis takes into account the methodological biases associated with studies establishing links between pollution and cancer by focusing, in particular, on those which present a precise measurement of exposure and those which take into account the main factors of risk of breast cancer. Originally ran on our sister brand in Quebec, Profession Santé. Translated from French.

Air pollution increases the risk of breast cancer

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