Lung cancer claims 160,000 lives per year and is becoming responsible for 27% of all cancer deaths in the United States.
While almost 90% of lung cancer cases are linked to smoking, the new study suggest that atmospheric oxygen plays a role in lung carcinogenesis.
Exploring the relationship of oxygen concentration with elevation, researchers found lower rates of lung cancer at higher elevations, a trend that did not expand to non-respiratory cancers, suggesting that carcinogen exposure occurs via inhalation.
Oxygen is highly reactive, and even when it is rapidly consumed by our cells, it results in reactive oxygen species, which can lead to cellular damage and mutation.
While oxygen comprises 21% of the overall atmosphere, lower pressure at higher elevations results in less inhaled oxygen which is an effect that notoriously bothers athletes at high altitudes.
For example, across US counties, elevation differences show a 34.9% decrease in oxygen from Imperial County, CA (-11 m) to San Juan County, CO (3,473 m).
The research revealed that as county elevation increased, lung cancer incidence decreased. The effect of elevation was significant with incidence of lung cancer, lowering by 7.23 cases per 100,000 individuals for every 1,000-meter (3,281 ft) rise in elevation, equaling approximately 13% of the mean lung cancer incidence of 56.8 cases per 100,000 individuals. A range of statistical techniques attested that the association was not due to chance.
The three most common cancers in the US are: breast, colorectal and prostate. The association of elevation with these non-respiratory cancers was either feeble or absent, supporting the hypothesis of elevation as an inhaled risk factor.
Environmental correlates of elevation, such as sun exposure and pollution measures, produced significantly substandard predictions of lung cancer incidence when compared with elevation itself.
Two previous epidemiological reports suggested that elevation-dependent oxygen variation was responsible for lower cancer mortality at high elevation. The current study was specifically designed to calculate the effect of elevation and benefited from a recent proliferation of high-quality county-level data.
The study examined over 30 variables and included 260 Western US counties. Using high-resolution census data, the researchers measured elevation values that showed population dispersion within each county and calculated the atmospheric exposure of each county’s populace.
If the entire United States situated at the elevation of San Juan County, CO (3,473 m), there would be 65,496 fewer new lung cancer cases per year.
While the researchers do not expect or recommend individuals to relocate based on these findings, identifying a universal and major risk factor could provide new insights into lung cancer etiology. From these insights, better treatments and preventative measures may come up.
Author: Blaine Pollock
Philanthropist and Businessman, Blaine Pollock is the creative force behind World News MD/Depression.net. Blaine is also the author of the newly released Children’s Book “O My Walter”. Find the magical book, “O My Walter” at www.omywalter.com