Sleep apnea is when a person has abnormal pauses in breathing or very low breathing during sleep.
Two additional trials were also shown at the the Congress and highlighted the association between cancer and sleep apnea.
For the first trial, the experts studied more than 5,600 patients from 7 sleep facilities in Spain. They used a hypoxaemia index to measure the severity of the sleep apnea in the patients. This type of index records how long the subjects have low oxygen levels in their blood while they are sleeping at night. "Low" was characterized by less than 90% oxygen saturation.
They found that patients who had oxygen saturation levels lower than 90% for more than 14% of their sleeping time had a higher than 50% risk of dying from cancer than those patients who did not suffer from sleep apnea. If the patients were young or male, the link between sleep apnea and dying from cancer was even greater.
A treatment option for sleep apnea patients is positive airway pressure (CPAP) therapy. This is a method that produces an air stream in order to make the upper airways stay open while the patient is sleeping. During the first study, if the patients were not using the positive airway pressure device on a regular basis, their risk of death from cancer was higher. The odds ratio was 2.56.
Dr Miguel Angel Martinez-Garcia, lead author, from the La Fe University Hospital in Valencia, Spain, commented:
"We found a significant increase in the relative risk of dying from cancer in people with sleep apnea. This adds to evidence presented earlier this year that found for the first time a link between cancer and sleep apnea mortality. Our research has only found an association between these disorders but this does not mean that sleep apnea causes cancer."
In the second study, the findings were relatively similar. The authors found a higher prevalence of every type of cancer in people who suffered from sleep apnea. The association remained the same after sex, age, weight and other factors were adjusted.
Lead author of the second study, Dr Francisco Campos-Rodriguez from Valme University Hospital in Seville, Spain, added: "Further studies are necessary to corroborate our results and analyze the role of CPAP treatment on this association. We hope the findings of our studies will encourage people to get their sleep apnea diagnosed and treated early to help maintain a good quality of life."
During the third study, the scientists worked with a mouse model of skin cancer, specifically melanoma, to analyze how tumors were spreading and if this had anything to do with sleep apnea.
Their findings revealed that the cancer spread more often in mice that had been exposed to intermittent air and had low levels of oxygen (which is similar to what happens in sleep apnea patients), than in the mice who had normal breathing patterns.
Professor Ramon Farre, lead author of the third study, concluded:
"The data from this study in animals strongly suggests a link between the spread of cancer and sleep apnea. This provides strong evidence to encourage further study in this area to understand in more detail the links between sleep apnea and cancer."
Written by Christine Kearney