The Impact of Air Pollution on Breast Cancer Survival: Insights from the Multiethnic Cohort Study


Breast cancer is a significant health concern affecting women from diverse racial and ethnic backgrounds. Researchers have been exploring various factors that could influence breast cancer outcomes, and one emerging area of interest is the potential link between air pollution and breast cancer survival. In this article, we delve into the findings of the Multiethnic Cohort (MEC) study by Iona Cheng and team from University of California, USA, which investigated how air pollution may affect breast cancer survival among women from different racial and ethnic groups.

Examining Air Pollution and Breast Cancer Survival

The Multiethnic Cohort study focused on women of African American, European American, Japanese American, and Latina American backgrounds who were diagnosed with breast cancer. Researchers sought to understand how exposure to certain air pollutants could impact their survival. The study used sophisticated models to estimate air pollution levels, including nitrogen oxides (NOx, NO2) and particulate matter (PM2.5, PM10), for a group of 3,089 breast cancer cases. These women, diagnosed between 1993 and 2013, primarily resided in Los Angeles County, California.

Analyzing the Data

To study the association between air pollution and mortality, the researchers used Cox proportional hazards models. This approach allowed them to assess the impact of time-varying air pollutants on various causes of death, including all-cause mortality, breast cancer-specific mortality, mortality from cardiovascular disease (CVD), and deaths not related to breast cancer or CVD. They also considered other important factors that could influence the results, known as covariates.

Findings from the Multiethnic Cohort Study

During the average follow-up period of 8.1 years, the study identified 1,125 deaths among the 3,089 breast cancer cases. These deaths included 474 related to breast cancer, 272 from cardiovascular disease, and 379 from causes other than breast cancer or CVD.

The analysis revealed concerning associations between air pollution and mortality. The study found that higher levels of nitrogen oxides (NOx and NO2) and particulate matter (PM2.5 and PM10) were linked to increased risks of death across different causes. Specifically:

  1. All-Cause Mortality: The risk of dying from any cause was found to be higher (Hazard Ratio [HR] range = 1.13-1.25) among women exposed to increased levels of these air pollutants.
  2. Breast Cancer-Specific Mortality: The risk of death specifically due to breast cancer was also elevated (HR range = 1.19-1.45) in association with higher levels of the studied air pollutants.
  3. Cardiovascular Disease (CVD) Mortality: The study observed a significant association (HR range = 1.37-1.60) between air pollution exposure and deaths related to cardiovascular disease.

Moreover, the positive association between air pollutants and breast cancer mortality remained consistent across different racial and ethnic groups, suggesting that this impact is not limited to one particular population.

Implications and Conclusion

The findings of the Multiethnic Cohort study indicate that air pollution can have harmful effects on breast cancer survival. Exposure to nitrogen oxides and particulate matter is associated with increased mortality risks for women diagnosed with breast cancer. The study’s results emphasize the importance of maintaining clean air and implementing regulations to reduce air pollution levels.

However, while this research sheds light on a potential connection between air pollution and breast cancer outcomes, it is essential to acknowledge that other factors may also influence survival rates. Socioeconomic factors, access to healthcare, lifestyle choices, and genetics are just a few examples of additional elements that might play a role in breast cancer outcomes.

Therefore, further investigations are needed to fully understand the complex interactions between air pollution and breast cancer survival. Future studies should consider the influence of socioeconomic factors to better isolate the impact of air pollution on breast cancer mortality.

In conclusion, this study highlights the significance of clean air laws and environmental policies in improving survival rates for women with breast cancer. Reducing air pollution is not only beneficial for respiratory and cardiovascular health but may also contribute to better outcomes for breast cancer patients. By prioritizing clean air initiatives, we can take a step toward creating a healthier environment for all, particularly for those facing breast cancer.


DOI: 10.1016/j.envint.2022.107088

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