Risk of lung cancer is much less in people living at higher altitudes, in both smokers and non-smokers, suggesting that oxygen may promote the incidence of lung cancer, reveals a new study.
Controlling for smoking, education, and numerous other variables associated with higher rates of cancer, a new study co-authored by a student at the Perelman School of Medicine at the University of Pennsylvania, has found that for every 1,000-meter rise in elevation, lung cancer incidence in the population living in that area decreased by 7.23 cases per 100,000 individuals. The 260 counties in 11 western states studied have a median lung cancer rate of 56.8 cases per 100,000 people.
The researchers did not find similar pronounced effects for elevation on colorectal, breast, and prostate cancer, all of which are also prevalent in the United States.
Kamen P. Simeonov said that lower atmospheric pressure at higher elevations results in less inhaled oxygen, sometimes as much as one-third less than low-elevation areas and this factor might explain why lung cancer incidence rates decrease as geographic elevation increases, but not rates for such equally pernicious cancers as colorectal, breast, and prostate.
Other factors studied include amount of sunlight, precipitation, temperature, and pollution. For lung cancer, elevation performed by far the best. The second best (radon) was 10 caret 8 times worse. Sunlight was over 10 caret 13 times worse.
The study is published online on PeerJ.