Sleep Apnea Increases Cancer Risk: Recent studies indicate the lack of oxygen can be a critical factor.

At the cellular level, a low-oxygen environment will cause normal cells to atrophy, or shrink. With cancer cells, it causes them to proliferate, or grow. These findings were brought to light recently when two new studies found that people with sleep apnea, a serious breathing disorder that occurs when a person's airway becomes obstructed during sleep, resulting in oxygen deprivation, have a higher risk of cancer.

Sleep apnea has been associated with a number of chronic diseases and conditions such as diabetes, cardiovascular disease, obesity and depression, but these two studies are the first to directly tie sleep apnea to increased cancer risk in humans.

The first study done on 5,600 patients from seven different sleep clinics in Spain revealed that in severe obstructive sleep apnea cases where a patient stops breathing for 10 seconds or longer for 30 episodes or more per hour, the patients had a 65 percent greater risk of developing cancer of any kind. The researchers in this study focused on measuring the hypoxemia index, which evaluates the amount of time a sleeper spent with less than 90 percent oxygen in the blood.

Of these patients, none had a cancer diagnosis when the study began. The research showed that the greater the extent of hypoxemia, or lack of oxygen during sleep, the more likely a person would receive a cancer diagnosis during the study. As time spent without oxygen increased, so too did cancer risk.

"This is really big news," says Dr. Joseph Golish, former chief of sleep medicine at the Cleveland Clinic, who was not involved in the research. "It's the first time this has been shown, and it looks like a very solid association.”

The second study followed 1,500 government workers in Wisconsin. The team at the University of Wisconsin School of Medicine and Public Health has been monitoring extensive overnight sleep studies since 1989. Their research recently revealed that people with moderate apnea (16 to 30 episodes per hour) were found to die from cancer at a rate twice that of people without the sleep breathing disorder. Those in the severe category (more than 30 episodes per hour) perished at a 4.8 times greater rate.

In both studies, the researchers ruled out the usual risk factors for cancer such as age, smoking, alcohol use, physical activity and weight. The association between sleep-disordered breathing and cancer remained even after they adjusted for these factors. "This is really striking," says Dr. F. Javier Neito, one the authors of the Wisconsin study. "It's hard to imagine that something we didn't control for is causing this."

It has been known for years that untreated sleep apnea reduces lifespan due to the strain that is put on the heart and other body systems. Although the research linking cancer to sleep apnea requires further study before it can be as strong as the well-documented relationship between sleep apnea and cardiovascular disease, Dr. Rod Willey, founder of Koala Center for Sleep Centers, states, "It is imperative that it is treated. The method of treatment may vary. But going untreated should not be an option."

Koala Center for Sleep Disorders – Biltmore offers a free educational class Oct. 18. For more information, phone 602-883-1931 at KoalaBiltmore.com.