Studies Mount Linking Sleep Apnea to Cancer Risk
There is mounting scientific evidence that severe obstructive sleep apnea (OSA) may be linked to a higher risk of dying from cancer. The results of three recent studies in Spain were presented in early September at the European Respiratory Society’s (ERS) Annual Congress in Vienna. The data presented by the Spanish researchers reinforces the results of previous studies which show similar links between severe OSA and cancer death.
Theory Behind the Link
When obstructive sleep apnea occurs, a person’s airway becomes obstructed during sleep, blocking air flow and causing the person to wake suddenly, often gasping for air. This can happen hundreds of times a night, causing a person’s blood oxygen level to drop abnormally low.
While scientists have yet to prove 100% that sleep apnea causes a higher risk of cancer death, more and more studies are showing the link. Many researcher theorize that the lack of adequate oxygen supply, known as intermittent hypoxia, caused by OSA causes increased vascular growth and tumor growth because poor breathing fails to oxygenate the cells sufficiently.
People with sleep apnea can be treated in a variety of ways including continuous positive airway pressure (CPAP) therapy, which generates a stream of air to keep the upper airways open during sleep, in addition to more recent techniques such as the Pillar Procedure® in-office treatment and the unobtrusive Provent® Device.
Three Spanish Studies
In a study led by Dr. Miguel Angel Martinez-Garcia from La Fe University Hospital in Valencia, Spain, more than 5,600 sleep apnea patients from seven different sleep clinics in Spain took part in a study to determine if there is a link between sleep apnea and cancer mortality. The severity of patients’ sleep apnea was measured, specifically, the number of times during the night that their blood oxygen level dropped below 90 percent oxygen saturation.
The results of the study showed that people with sleep apnea who spent more than 14 percent of their sleep time with oxygen saturation levels below 90 percent usually had severe sleep apnea, and were approximately double the relative risk of dying due to cancer than people without sleep apnea. The results also showed a significant increase in the relative risk of dying from cancer in people with sleep apnea. The association was even higher in men and younger people.
Lead author Dr. Miguel Angel Martinez-Garcia from La Fe University Hospital in Valencia, Spain, said that, although their research found an association between sleep apnea and cancer, the results do not mean that sleep apnea causes cancer. He added that it adds to growing evidence that there is a clear link between sleep apnea and cancer mortality.
More Research Reinforces Relationship
Research from two other Spanish studies presented at the European Respiratory Society’s Annual Congress showed an increase in cancer incidence in humans, as well as an association between sleep apnea and the spread of cancer in mice.
The second study showed an increase in all types of cancer in people with severe sleep apnea, even when other factors such as age, sex and weight were taken into account.
In a third study, Spanish researchers used mice to study the spread of melanoma skin cancer (metastasis), and whether this was associated with sleep apnea. The results showed that the spread of cancer was more abundant in mice that had experienced low levels of oxygen as in sleep apnea, than those who breathed normal air during the experiment.
According to the study’s lead author, Professor Ramon Farre from the University of Barcelona in Spain, the results of the mouse study strongly suggests a link between sleep apnea and the spread of cancer, and encourages further research to better understand the links between sleep apnea and cancer.
Read the full study, “Sleep Apnoea Linked with Increased Risk of Cancer Death.”
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