Two American researchers published data in late 2014 investigating the link between altitude and lung cancer. For over 40 years, scientists have been trying to figure out why living at higher elevations protects from lung cancer.
With an impressive look at US lung cancer incidence data county by county, Kamen Simeonov and Daniel Himmelstein theorize in the open journal PeerJ that lack of oxygen at higher altitudes has an inverse correlation with lung cancer incidence. For every 1000 meter rise (3281 feet) in elevation, the incidence decreased approximately 12.7%, or by 7.23 cases per 100,000.
There are 4 types of cancer in the United States which exceed 100,000 new cases per year: prostate, breast, colorectal, and lung. Lung cancer carries the worst prognosis in general. Most lung cancer cases stem from smokers, but 10-15% of incidences begin in non-smokers. Aside from smoking, the researchers discovered, elevation is the second largest predictor of lung cancer incidence.
Simeonov and Himmelstein believe higher elevation has a protective effect because of the decrease in atmospheric oxygen. While this seems counter-intuitive, oxygen has been shown to generate intracellular reactive oxygen species (ROS) which damage cells and can lead to cancer. Such oxidative DNA damage is most prominent in the lungs, where oxygen reacts directly with tissue. Other possible causes of the elevation correlation, including increased sun exposure at higher altitudes, were ruled out.