TUESDAY, Jan. 13, 2015 (HealthDay News) -- Americans who live in the mountains seem to have lower rates of lung cancer than those closer to the beach -- a pattern that suggests a role for oxygen intake, researchers speculate.

Their study of counties across the Western United States found that as elevation increased, lung cancer rates declined.

For every 3,300-foot rise in elevation, lung cancer incidence fell by more than seven cases per 100,000 people, researchers reported Jan. 13 in the online journal PeerJ.

No one is saying people should head to the mountains to avoid lung cancer -- or that those who already live there are in the clear.

"This doesn't mean that if you live in Denver, you can go ahead and smoke," said Dr. Norman Edelman, senior medical advisor to the American Lung Association.

It's not even certain that elevation, per se, is the reason for the differing lung cancer rates, said Edelman, who was not involved in the research.

"But this is a really interesting study," he said. "It gives us useful information for further research."

Kamen Simeonov, one of the researchers on the study, agreed. "Should everyone move to a higher elevation?" he said. "No. I wouldn't make any life decisions based on this."

But the findings do support the theory that inhaled oxygen could have a role in lung cancer, said Simeonov, a graduate student in the bioinformatics program at the University of California, San Francisco.

As elevation increases, air pressure dips, which means people inhale less oxygen, Simeonov explained. And while oxygen is obviously vital to life, the body's metabolism of oxygen can have some unwanted byproducts -- namely, reactive oxygen species.

Over time, those substances can damage body cells and contribute to disease, including cancer.

Some recent research on lab mice has found that lowering the animals' exposure to oxygen can delay tumor development. But no one knows whether taking in less oxygen would affect humans' cancer risk.

According to Edelman, the oxygen theory has some "biological plausibility." But for now, it's just a theory, he said.