Two studies have just linked sleep apnea to cancer. One study showed that the more severe the sleep apnea, the more likely a person will receive a diagnosis of cancer. In the other, people who already had cancer were more likely to die of it if they also had serious sleep apnea. Moderate sleep apnea doubled the risk of cancer death and severe sleep apnea nearly quintupled it. The studies did not investigate whether treating sleep apnea with CPAP reverses these risks.
[American Thoracic Society International Conference, in San Francisco, May 2012]