Women face heightened breast cancer risk from poor air quality

Prolonged exposure to air pollution appears to put women at increased risk of breast cancer, according to data from the French E3N cohort.

Over 22 years of follow-up, a significant positive association was seen between exposure to fine particulate matter (PM_2.5) and breast cancer. With each incremental increase of 10 µg/m³  in PM_2.5, the odds of having breast cancer increased by 28 percent (odds ratio [OR], 1.28, 95 percent confidence interval [CI] 1.00–1.63). [ESMO Congress 2023, abstract 238MO]

Meanwhile, exposure to PM₁₀ and NO₂ showed no association with breast cancer risk (for an increment of 10 µg/m³: OR, 1.09, 95 percent CI, 0.92–1.30 and OR, 1.05, 95 percent CI, 0.97–1.13, respectively).

“No difference by hormone receptor status nor effect modification by menopausal status was observed,” reported Dr Beatrice Fervers of Comprehensive Cancer Center Léon Bérard, Lyon, France, at ESMO Congress 2023.

“This is the first study investigating breast cancer risk and long-term air pollutant exposure from both the residential and workplace location histories of the women. Findings were comparable when using only concentration estimates at the residence and when increasing proportion of daily time spent at the workplace,” Fervers said.

A total of 2,419 women with breast cancer and 2,984 women without breast cancer from the prospective French E3N cohort were included in the nested-case analysis. These women were matched according to age, department of residence, date and menopausal status at blood collection.

Annual mean PM_2.5, PM₁₀, and NO₂ levels were estimated using a Land Use Regression model. These estimates were assigned to women based on geocoded residential and workplace addresses. The average exposure to pollutants was calculated by taking into account the amount of time the women spent at home (80 percent) and at work (20 percent) during the study period (1990–2011).

Genotoxic

The findings are consistent with those of two other studies that have shown a link between poor air quality exposure and breast cancer risk. [Cancer Epidemiol Biomarkers Prev 2023;32:105-113; J Natl Cancer Inst 2023;doi:10.1093/jnci/djad170]

Commenting on the study, Dr Shani Paluch-Shimon of Hadassah University Hospital in Jerusalem, Israel, said in a statement: “Breast cancers, other than hereditary diseases, have multifactorial risk factors and it is the cumulative exposure over time that increases an individual’s risk.

“We know that there is a biological rationale behind the link between air pollution and breast cancer risk, given that small particulate matter is genotoxic, can lead to endocrine destructive behaviours and can affect breast tissue density. So, what we are seeing with these latest data is part of a bigger picture of cancer risk and we need to understand how it fits together,” she told the ESMO Daily Reporter.

Paluch-Shimon highlighted the urgent need to address air pollution and develop effective public policies to improve air quality. The recent surge in forest fires in certain regions, a series of events that reflects the increasing impact of climate change on the environment, is all the more reason to act, she added.

“We also need to consider that while air pollution is a global problem, it is one that is likely to disproportionately impact many low- to middle-income countries, which are already at a disadvantage in terms of access to affordable healthcare,” according to Paluch-Shimon.