MADRID – according to a new analysis of the XENAIR study presented at the European Society of Medical Oncology (ESMO) Congress 2023. Béatrice Fervers, MD, PhD, head of the environmental cancer prevention department at the Léon Bérard Center, Lyon, France, presented her findings.
“To our knowledge, this study is the first to examine the risk of breast cancer associated with long-term exposure of subjects to atmospheric pollution both at home and in the workplace, estimated using a very small spatial resolution [statistical] model,” said the researchers.
“Our data showed a statistically significant association between long-term exposure to fine particulate matter air pollution, at home and at work, and risk of breast cancer. This [finding] contrasts with previous research that looked only at fine particulate exposure where women were living and showed small or no effects on breast cancer risk,” said Dr. Fervers in a press release issued before the Congress.
The XENAIR study carried out on the prospective, longitudinal E3N cohort a year ago showed an increased risk for breast cancer after exposure to five atmospheric pollutants. Notably, it showed an increased risk in women exposed to BaP and PCB153, two pollutants classed as endocrine-disrupting chemicals, during perimenopause.
Increased linear risk
In this new analysis, exposure to PM2.5, PM10, and NO2 pollution at home and in the workplace of 2,419 women with breast cancer was compared with that of 2,984 women without breast cancer during the period from 1990 to 2011.
This was a case-control study in which participants were matched by department of residence in France, age (± 1 year), date (± 3 months), and menopausal status at the time of the blood draw.
Breast cancer risk increased by 28% when exposure to fine particulate (PM2.5) air pollution increased by 10 mcg/m3. The increment is approximately equivalent to the difference in PM2.5 particulate concentration typically seen in rural versus urban areas of Europe.
Smaller increases in breast cancer risk were also recorded in women exposed to high levels of larger particulate air pollution (PM10 and NO2).
No change in effect was seen according to menopausal status. Analyses that examined hormone receptor status showed a positive but not significant association for PM2.5 in cases of estrogen receptor positive breast cancer.
Dr. Fervers and colleagues plan to investigate the effects of pollution exposure during the commute to get a complete picture of effects on breast cancer risk.
Regulators respond
Charles Swanton, PhD, a clinician scientist at the Francis Crick Institute, London, emphasized the importance of these new results for breast cancer. At last year’s ESMO Congress, he explained how particulate matter air pollution caused tumor proliferation in patients with a certain type of genetic mutation.
“Fine particle pollutants can penetrate deep into the lungs, enter the bloodstream, and be absorbed into breast and other tissue. There is already evidence that air pollutants can change the architecture of the breast. It will be important to test if pollutants allow cells in breast tissue with pre-existing mutations to expand and drive tumor promotion, possibly through inflammatory processes, similar to our observations in nonsmokers with lung cancer,” said Dr. Swanton in the ESMO press release.
“It is very concerning that small pollutant particles in the air and indeed microplastic particles of similar size are getting into the environment when we don’t yet understand their potential to promote cancer. There is an urgent need to set up laboratory studies to investigate the effects of these small air pollutant particles on the latency, grade, aggression, and progression of breast tumors,” he added.
“There is now strong epidemiological and biological evidence for the link between PM2.5 particulate exposure and cancer, and there are good clinical and economic reasons for reducing pollution to prevent cancers,” said Jean-Yves Blay, MD, PhD, director of public policy for ESMO.
Following a proposal from the European Commission in October 2022 to reduce the limit for PM2.5 particulates in the air from the current 25 mcg/m3 to 10 mcg/m3 by 2030, ESMO urged a further reduction in the PM2.5 limit to 5 mcg/m3, in line with the World Health Organization’s air quality guidance, according to the press release.
“Reducing PM2.5 particles in the air to the WHO recommended level is critical because of their association with a variety of tumor types, including breast cancer,” Dr. Blay added.
In September 2023, the European Parliament adopted in a plenary session its report on the ongoing revision of the EU Ambient Air Quality Directives, which reflects ESMO’s recommendations to set the annual limit value for PM2.5 at 5 mcg/m³. This adoption opens interinstitutional negotiations between the legislators (the European Parliament, European Commission, and EU Council) to agree on the final text of the directive.
“By supporting our requests with solid scientific evidence, we are offering a new dimension to health public policy. The work is not over, and change will not happen overnight, but we are moving in the right direction,” concluded Dr. Blay.
The new analysis of the XENAIR study was funded by ARC Foundation for cancer research; the French Agency for Food, Environmental, and Occupational Health and Safety; French National League against Cancer; and Fondation de France, an independent administrative agency. The authors report no relevant financial relationships.
This article was translated from the Medscape French edition and a version appeared on Medscape.com.