TOPLINE: 

A recent study found that long-term exposure to fine particulate matter ≤ 2.5 μm (PM2.5) is associated with an increased risk for breast cancer, with the highest risk observed among White women.

METHODOLOGY:

• Studies have suggested that exposure to air pollution — specifically PM2.5 — may increase the risk for breast cancer, but data are largely in populations of White women.
• The current analysis explored the potential risk among a more racially and ethnically diverse group.
• The study included 58,358 women (median age, 60.4 years at enrollment) from the California Cancer Registry, followed over an average of 19.3 years. Overall, 35% were African American, 39% were Latino, 15% were White, and 10% were Japanese American.
• Researchers measured PM2.5 exposure using satellite-based data and geocoded addresses. Other pollutants, such as PM10, NO2, NOX, and CO, were also tracked using Environmental Protection Agency data.

TAKEAWAY:

• A total of 3524 invasive breast cancer cases were diagnosed over an average follow-up period of 19.3 years. PM2.5 exposure was associated with a 28% increased risk for breast cancer overall (hazard ratio [HR], 1.28; 95% CI, 1.08-1.51).
• When looking at risk by racial/ethnic group, the association between PM2.5 exposure and breast cancer risk was strongest among White women (HR, 1.67). PM2.5 exposure was also associated with a higher risk for breast cancer among African American women (HR, 1.14; 95% CI, 0.89-1.46) and Latino women (HR, 1.34; 95% CI, 0.94-1.92), but the associations were not significant.
• Overall breast cancer incidence was also positively associated with exposure to NO2, NOX, and CO (HRs, 1.09-1.11), but the associations were not significant. A meta-analysis of this study and ten other cohorts estimated a 5% increased breast cancer incidence per 10-unit increase in PM2.5 (HR, 1.05).

IN PRACTICE:

“Collective findings suggest that PM2.5 exposure should be considered a risk factor for breast cancer, and curtailing air pollution exposures at the population level using regulatory strategies should be a priority,” the authors concluded.

SOURCE:

The study, led by Anna H. Wu, PhD, MPH, Keck School of Medicine, University of Southern California, Los Angeles, was published online in the Journal of Clinical Oncology.

LIMITATIONS:

The study did not include data on nonresidential exposures or residential history before cohort entry, which limited the assessment of earlier exposures. The study also lacked information on specific sources of PM emissions, as well as an explanation for why White women had the highest breast cancer risk compared with other racial/ethnic groups.

DISCLOSURES:

The study was supported by grants from the Health Effects Air Pollution Foundation, the National Cancer Institute, USC Environmental Exposures, Host Factors, and Human Disease, and the California Air Resource Board. One author disclosed being an associate editor for the Journal of Clinical Oncology. No other potential conflicts of interest were reported.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.