Research: Association Between Sleep Apnea & Cancer
Approximately 28 million people in the US suffer from sleep apnea, making it one of the most prevalent sleep disorders. The condition, which causes a person’s airways to become completely or partially blocked while asleep, has been linked with an increased risk of accidents, cardiovascular disease, diabetes and obesity. And now, two recent studies that are being called “big news”, “very solid”, and “striking” have shown an association between sleep apnea and cancer.
The first study, which began following about 5,200 cancer-free patients at sleep clinics in Spain, found that those with the most severe forms of sleep apnea had a 65% increased risk of being diagnosed with any type of cancer during the 7-year study period. The overall trend observed by the researchers was that the worse the sleep apnea condition (measured by the levels of oxygen depletion), the more likely a person would receive a cancer diagnosis during the study period.
The second study, which examined 22-year mortality data on about 1,500 subjects from the Wisconsin Sleep Cohort, showed that the more severe a person’s breathing problems, the greater the likelihood of dying from cancer. People with mild sleep apnea -- five to 14.9 episodes of low or no oxygen in an hour -- had a 10 percent increased risk of cancer death, while those with moderate sleep apnea -- 15 to 29.9 episodes of low or no oxygen in an hour -- had double the risk of cancer death. Those with severe sleep apnea -- more than 30 episodes of low or no oxygen in an hour -- had a 4.8 times higher risk of cancer death.
The studies, which were presented at the American Thoracic Society International Conference in San Francisco, are preliminary and the authors mention that more research is needed. It’s also worth noting that the researchers found only an association between sleep apnea and cancer, and that the results do not prove that sleep apnea causes cancer.
However, researchers did speculate that sleep apnea, which lowers blood oxygen levels at night, might be causing tumors to sprout more blood vessels to compensate, allowing them to grow faster.
Positive Note: Treatment and Importance of Sleep Apnea Screening
One positive note, researchers speculate that treatments for sleep apnea, such as the use of a continuous positive airway pressure (CPAP) machine, may reduce the risk by increasing blood oxygen levels.
Since many cases of sleep apnea are undiagnosed, the research serves as an important reminder to anyone that might suspects they have sleep apnea, to see their doctor for a screening. The screening, which typically involves an overnight stay at a sleep clinic, can identify if you have sleep apnea and determine what the best course of treatment is.
Some Indications of Sleep Apnea
Two of the most common indications of sleep apnea are: snoring and severe daytime fatigue (i.e., not feeling rested even after getting a long-block of sleep.)
Some of the risk factors for developing sleep apnea include being overweight, smoking, drinking alcohol (especially before going to bed), and taking sleeping pills. Moderate sleep deprivation has been found to aggravate sleep apnea. All of these factors are more prevalent among shiftworkers than in the general population.
Anahad O’Connor, “Sleep Apnea Tied to Increased Cancer Risk,” New York Times, May 20, 2012 - http://well.blogs.nytimes.com/2012/05/20/sleep-apnea-tied-to-increased-cancer-risk/
School of Medicine and Public Health, University of Wisconsin-Madison, “Sleep Apnea Associated with Higher Mortality from Cancer,” May 21, 2012 -http://www.med.wisc.edu/news-events/news/sleep-apnea-associated-with-higher-mortality-from-cancer/37687
Serena Gordon, “Sleep Apnea Linked to Higher Cancer Death Risk” HealthDay, May 20, 2012 - http//www.philly.com/philly/health/HealthDay664843_20120520_Sleep_Apnea_Linked_to_Higher_Cancer_Death_Risk.html