Air pollution may shorten the lives of lung cancer patients, a new study suggests.
Researchers led by Sandrah Eckel, who's with the department of preventive medicine at the University of Southern California in Los Angeles, analyzed data from more than 352,000 people in California who were diagnosed with lung cancer between 1988 and 2009.
Higher exposure to the pollutants nitrogen dioxide, ozone and airborne particles was associated with an increased risk of early death. The association was strongest in patients with early stage disease, particularly adenocarcinoma, which accounts for 80 percent of lung cancer cases, the researchers said.
Early stage patients with greater exposure to pollutants survived on average 2.4 years compared to 5.7 years for those with low exposure, the study found.
The study was published online Aug. 4 in the journal Thorax.
Since this was an observational study, no firm conclusion can be drawn about cause and effect, the researchers said. But they noted that the International Agency for Research on Cancer classifies air pollution as a cancer-causing agent.
"This study, along with two other previously published analyses on the impact of air pollution on cancer survival, provide compelling initial evidence that air pollution may be a potential target for future prevention and intervention studies to increase cancer survival," Dr. Jaime Hart wrote in an accompanying journal editorial.
Hart is an epidemiologist at Brigham and Women's Hospital in Boston.