Both particulate and gaseous air pollutants were linked with subtypes of lung cancer, according to a study published by Diver et al in Environmental Pollution. The analysis, led by investigators from the Barcelona Institute for Global Health (ISGlobal) and the American Cancer Society, showed that nitrogen dioxide was associated with adenocarcinoma and ozone was associated with large cell carcinoma, while fine particulate matter was associated with all subtypes of lung cancer.
“We have observed that air pollution is not associated with all types of lung cancer in the same way,” explained senior study author Michelle C. Turner, PhD, Associate Research Professor at ISGlobal in Barcelona, Spain. “Our results reinforce the importance of integrating local air quality into health-care plans and assessing each patient’s environmental exposure to identify additional risks.”
Background and Study Methods
The researchers looked at patient data from participants in the American Cancer Society's Cancer Prevention Study-II Nutrition cohort (n = 122,442), which began in 1992 and required participants to update their information every 2 years through 2017. The study estimated the annual exposure to various air pollutants—including fine particulate matter (PM2.5), coarse particulate matter (PM10), ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO)—and variation over time according to individual factors for each participant.
“We used national air quality data combined with satellite and land-use information updated over the 25 years of the study,” explained first and corresponding study author W. Ryan Diver, PhD, of both ISGlobal and the American Cancer Society. “This allowed us to relate exposure to pollution to the risk of developing different lung cancer subtypes, as well as survival after diagnosis in specific patient subgroups.”
The researchers used extended Cox regression models to assess time-varying pollutant exposures in accordance with the risk of lung cancer by subtype and survival outcomes.
Key Findings
A total of 4,282 lung cancers were diagnosed in the cohort between 1992 and 2017. In terms of pollutants, PM2.5 (hazard ratio [HR] = 1.06; 95% confidence interval [CI] = 1.02–1.11) plus NO2, O3, and SO2 (increased risk by 4% to 7%) were associated with lung cancer incidence.
According to lung cancer subtype, NO2 was associated with adenocarcinoma (HR = 1.07; 95% CI = 1.00–1.14) and O3 was associated with large cell carcinoma (HR = 1.13; 95% CI = 0.97–1.33), whereas PM2.5 was associated with all subtypes of lung cancer. No associations were found between any of the pollutants analyzed and small cell carcinoma.
Few associations were evident in the research for recent pollutant exposure and overall or lung cancer–specific mortality. In localized cancers, SO2 was associated with lung cancer–specific death (HR = 1.18; 95% CI = 1.00–1.40), and in regional cancers, PM10 was also associated with lung cancer–specific death; these findings were elevated for current smokers, but were not considered statistically significant.
DISCLOSURE: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
