PM2.5 Exposure Linked to Lung Cancer in Non-Smoking Women

A potential link between exposure to particulate matter smaller than 2.5 micrometers (PM2.5) and lung cancer development in women who have never smoked has been revealed by recent research. This significant finding, presented at the 2024 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer (IASLC), shows notable differences in lung cancer diagnosis stages among non-smokers with EGFR mutations, specifically among women (1^✔ ✔Trusted Source
PM2.5 Exposure May Affect Lung Cancer in Women Who Have Never Smoked

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PM2.5 as a Carcinogen

In 2013, the International Agency for Research on Cancer (IARC) classified outdoor air pollution, including PM2.5 particles, as a Group 1 carcinogen. This classification places air pollution in the same category as tobacco use for its cancer-causing potential. However, despite the clear connection between tobacco use and most lung cancer cases, the reason some non-smokers develop lung cancer has remained unclear until now.

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Impact of PM2.5 Exposure on Lung Cancer Risk in Non-Smokers

Dr. Yixian Chen and her team at the British Columbia Cancer Research Institute set out to investigate how different durations of PM2.5 exposure may impact lung cancer risk in individuals who never smoked. Specifically, they wanted to understand whether recent or long-term exposure to PM2.5 played a role in lung cancer development, particularly in relation to EGFR mutation status.

The study involved 255 newly diagnosed lung cancer patients who had never smoked. Participants provided detailed residential histories, from birth to the date of diagnosis, allowing researchers to track their exposure to PM2.5 pollution. Each address was geocoded and analyzed for PM2.5 levels using satellite data, chemical transport models, and ground-based measurements. The team focused on annual exposure data from 1996 onward, when reliable global air pollution data became available.

Key Findings of the research are:

• Significant Gender Differences: The study revealed a marked difference in how PM2.5 exposure affected men and women. Women diagnosed with stage IV lung cancer had significantly higher rates of EGFR mutations compared to those diagnosed at earlier stages.
• Cumulative PM2.5 Exposure and EGFR Mutations: Among women, a clear link was found between recent cumulative PM2.5 exposure (within the last 3-5 years before diagnosis) and EGFR mutation status. Women with EGFR mutations had significantly higher PM2.5 exposure levels compared to those without such mutations.
• 3-Year Cumulative Exposure: Women with EGFR mutations had a 3-year cumulative exposure of 19.0 μg/m³ compared to 17.3 μg/m³ for those without mutations.
• 5-Year Cumulative Exposure: Women with EGFR mutations also showed a higher 5-year cumulative exposure (33.7 μg/m³) than those without (29.5 μg/m³).
• No Significant Findings in Men: Interestingly, these associations between PM2.5 exposure and EGFR mutations were not found in men who had never smoked, suggesting that women may be more susceptible to the effects of recent PM2.5 exposure on lung cancer development.

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Long-Term Exposure Not Linked to EGFR Mutations

While recent PM2.5 exposure was associated with EGFR mutation status in women, long-term cumulative exposure (10, 15, and 20 years) did not show the same association. This indicates that short-term, high-exposure periods might be more relevant in assessing lung cancer risks for non-smoking women than prolonged exposure over decades.

Dr. Chen emphasized the importance of understanding how recent PM2.5 exposure contributes to lung cancer in non-smokers, particularly in women. The findings suggest that exposure levels over 3 to 5 years may be critical in assessing lung cancer risks. However, further studies are needed to confirm whether these shorter measurement periods are sufficient for evaluating lung cancer risks associated with air pollution.

This research provides new insights into how air pollution, particularly PM2.5, may contribute to lung cancer in women who have never smoked. With significant gender-specific differences observed in lung cancer diagnosis stages and EGFR mutation status, the study underscores the need for more targeted risk assessments based on recent exposure to pollutants like PM2.5.

Reference:

1. PM2.5 Exposure May Affect Lung Cancer in Women Who Have Never Smoked - (https://www.iaslc.org/iaslc-news/press-release/pm25-exposure-may-affect-lung-cancer-women-who-have-never-smoked)

Source-Medindia