Patients With Early Stage Lung Cancer More Susceptible to Dying Due to Air Pollution

Survival in patients with early-stage lung cancer, particularly those with adenocarcinomas, may be shortened by air pollution, according to a study published in the journal Thorax.

While air pollution is a known risk factor for lung cancer, it’s impact on survival in those diagnosed with the disease is not very clear. The current study was designed to answer that question.

The study included 352,053 patients with newly diagnosed lung cancer, diagnosed between 1988 and 2009 and included in the California Cancer Registry. The mean patient age was 69 years at diagnosis, and more than 50% of the cancers were detected at an advanced stage.

The authors found that the survival time for patients with early stage or localized disease was 3.6 years; this fell by more than 50% to 1.3 years for patients whose disease has spread regionally, and just 4 months for those with distant metastases. Survival time was shortest for patients with small and large cancers (average 1.5 years), while those with an adenocarcinoma survived longer (about 5 years).

The average residential ambient air pollution concentrations were documented for each participant during the follow-up; this included exposure to nitrogen dioxide (NO₂), ozone (O₃), particulate matter—the information was gathered from the US Environmental Protection Agency. More than 45% of the study participants lived more than 1500 meters from a major interstate highway and not more than 10% were within a 300-meter radius of a major highway.

After accounting for all of these variables, the authors found that greater the exposure to each of the 4 pollutants, higher was the risk of death and shorter the 5-year survival in lung cancer patients. Significantly, the risk of death was the highest among patients with early stage disease, with an average survival of 2.4 years with high exposure to particulate matter and 5.7 years for those with low exposure. Further, risk of death from any cause was 30% more for NO₂ and 38% greater for smaller-sized particulate matter. O₃ did not seem to have a significant bearing on survival, however.

Patients with advanced stage disease fares poorly, irrespective of pollutant exposure.

The authors conclude that their findings support the hypothesis that exposure to air pollution shortens survival in lung cancer patients and they recommend prospective studies that can evaluate the impact following exposure reduction.

In an accompanying editorial in the same issue, Jaime E. Hart, SCD, from Brigham and Women’s Hospital, writes that the study provides compelling evidence that reducing air pollution could be a preventive intervention to improve survival in lung cancer.

Reference

Eckel SP, Cockburn M, Shu Y, et al. Air pollution affects lung cancer survival [published online August 4, 2016]. Thorax. doi:10.1136/thoraxjnl-2015-207927.