Lung cancer has been largely linked to activities such as smoking, but a new study suggests atmospheric oxygen can also play a significant role in lung carcinogenesis.
When oxygen is quickly consumed by our cells it can result in reactive oxygen species (ROS), which can lead to both cellular damage and mutation, a press release reported. Oxygen makes up about 21 percent of the overall atmosphere, but lower pressures at higher elevations can lead to less inhaled oxygen.
"Were the entire United States situated at the elevation of San Juan County, CO (3473 meters), we estimate 65,496 fewer new lung cancer cases would arise per year," the researchers stated.
To make their findings researchers compared cancer incidences across regions of varying elevation in the Western U.S. They found that as elevation increased, risk of lung cancer tended to significantly decrease. The team observed a decrease of 7.23 cases per 100,000 individuals for every 3,281 feet rise in elevation. The team did not find a correlation between altitude and non-respiratory cancers such as those found in the breasts, colon, or prostate. Environmental correlations such as sun exposure and fine particulate matter were found to be inferior predictions of lung cancer risk when compared with altitude.
The findings back up past studies that have shown oxygen variation was responsible for lower cancer mortality at high elevation The recent study relied on 30 variables that enabled the inclusion of 250 Western U.S. counties using high resolution census data.
The researchers hope future studies on the subject will focus on oxygen's role in human carcinogenesis and analyze the phenomenon across diverse regions to provide further epidemiological evidence. The researchers noted they do not expect anyone to relocate as a result of the study's findings, but finding a universal link between these two factors could provide new insights into the causes of lung cancer.
The findings were published in a recent edition of the open access journal PeerJ.
