Does Sleep Apnea Cause Cancer? New Evidence Suggests Women Could Be At More Risk

The study did not look at a specific kind of cancer.

The study was led by Athanasia Pataka, assistant professor of respiratory medicine at Aristotle University in Greece. "Recent studies have shown that low blood oxygen levels during the night and disrupted sleep, which are both common in OSA, may play an important role in the biology of different types of cancers. But this area of research is very new, and the effects of gender on the link between OSA and cancer have not been studied in detail before" she said in a release.

OSA, where the airways close completely or partially many times during sleep, reduces the levels of oxygen in the blood, and common symptoms include snoring, disrupted sleep and feeling excessively tired. The new study seems to suggest that people who experience more closures of the airways during sleep and whose blood oxygen saturation levels drop below 90 percent more frequently are more likely to be diagnosed with cancer than people without OSA. In total, the participants included 5,789 women and 13,767 men, who were also assessed for their age, smoking status, BMI, and level of alcohol use, as these lifestyle factors are known to affect cancer risk.

Although the link between sleep and cancer is a relatively new area of study, this isn't the first time that the poor quality of sleep caused by sleep apnea has been looked at as a possible driver of cancer risk, and associations have been made before, particularly with lung and colorectal cancers. Melanoma and kidney cancer as also thought to have a potential association with sleep.

Dr Amanda Phipps, an epidemiologist and researcher at Fred Hutchinson Cancer Research Center in Seattle who studies the possible relationship between OSA and cancer, told SurvivorNet that we shouldn't read too much into the findings of this study alone.

"This is a cross sectional analysis," she explained, "so it shows just one snapshot of each participant. So it's really hard to work out what's the chicken and what's the egg, whether the apnea or the cancer came first."

The gender difference between cancer risks in the study is also an open question at the moment.  In a press release Professor Pataka explained, "Our study did not explicitly explore the causes of different cancers, but cancer may differ between men and women because of factors such as how hormones affect tumor growth; how the different types of cancer that were more prevalent in men and women are affected by low blood oxygen levels; or how gender specific exposure to cigarette smoking may play a role."

"Not all cancers are created equally," Dr Phipps notes. "The association between OSA and cancer may well be different depending on the type of cancer." This particular study didn't differentiate between types of cancer.

But while it may not have all the answers, Dr Phipps also points out that the ESADA study, when viewed in combination with studies already done, does add to a body of work that is supportive of a relationship between sleep apnea and cancer.

"The oxygen deprivation caused by sleep apnea can lead to DNA damage and inflammation" she explained. DNA damage is a known cause of cancer, and chronic inflammation has been associated with several types of cancer. "So there are physiological reasons why OSA could lead to cancer. Sleep is your body's time to repair, so if you're getting less sleep because of apnea, and less oxygen, the body might not be getting all of the tools and the time it could need to repair DNA."

It is too early to say anything for sure, but it time this could become bigger news for the  estimated (mostly undiagnosed) twenty million Americans with sleep apnea. And cancer aside, as Dr Phipps points out, "there are so many health reasons to get a good night's sleep."

Learn more about SurvivorNet's rigorous medical review process.

---