A new study shows that the incidence of lung cancer is lower at higher elevations. "For every 1,000 m rise in elevation, lung cancer incidence decreased by 7.23 cases per 100,000 individuals." User Kooby2, in the Reddit Science subreddit, 15 Jan 2015
Does inhaled oxygen cause cancer? Decreased lung cancer at higher altitudes suggests so. User dhimmel, in the Reddit Science subreddit, 13 Jan 2015