Sleep apnea is a problem that goes well beyond annoying your partner with loud snoring. Research is showing it can raise risk for heart attacks, stroke and diabetes. Now, a new study finds it can make a person five times more likely to die from cancer.
For the study, which will be published in an upcoming issue of the American Journal of Respiratory and Critical Care Medicine, researchers collaborated with Spanish scientists to examine 22-year mortality data on 1,522 people enrolled in a long-running "Wisconsin Sleep Cohort" study. The data looked at Washington state employees since 1989.
Every four years, the subjects underwent overnight sleep studies, including a polysomnography - an all-night recording of sleep and breathing. The researchers determined - after accounting for other risk factors like smoking and obesity - that people with severe sleep apnea were 4.8 times more likely to die from cancer. The association was stronger among non-obese subjects, compared with obese ones.
The study was a collaboration with other research from the University of Barcelona, that found inadequate oxygen - which is indicative of sleep apnea and sleep-disordered breathing (SDB) - could increase tumor growth in mice. Like the human study, the effect was stronger in lean mice, compared with obese ones.
"Clearly, there is a correlation, and we are a long way from proving that sleep apnea causes cancer or contributes to its growth," study author Dr. F. Javier Nieto, chair of the department of population health sciences at the University of Wisconsin-Madison School of Medicine and Public Health, said in a news release. "But animal studies have shown that the intermittent hypoxia (an inadequate supply of oxygen) that characterizes sleep apnea promotes angiogenesis--increased vascular growth--and tumor growth. Our results suggest that SDB is also associated with an increased risk of cancer mortality in humans."