Night-Time Breathing Disorders A Cancer Risk?
New study finds an association between low oxygen levels and cancer
Posted Jan 03, 2013
Obstructive sleep apnea, a condition in which the soft portion of the throat collapses during sleep and blocks the flow of air into the lungs, causes lots of problems for a great many people. These include excessive daytime sleepiness, high blood pressure, diabetes, and heart disease. Now, it appears that men under the age of 65 who suffer from obstructive sleep apnea may also have an increased risk of cancer, according to a new study published in the American Journal of Respiratory and Critical Care Medicine.
Researchers analyzed the records of almost 5,000 adults patients who were evaluated for possible obstructive sleep apnea over a four-year period at seven teaching hospitals in Spain. The researchers found that the more time men under the age of 65 spent with their blood oxygen levels lower than 90 percent, the higher was their incidence of cancer. This relationship was also true for obstructive events scored on sleep studies.
What is not clear from this study’s findings is the question of cause and effect. Were those patients with cancer sicker to begin with, and have abnormalities in their oxygen levels because of this? Or did the low oxygen levels in these patients lead to the emergence of their cancer?
Hypoxia (low oxygen levels) causes the expression of a hormone called hypoxia-inducible factor (HIF) in cells. HIF can induce the growth of tumor cells, promote their spread throughout the body, and make them resistant to treatment: all which can lead to a more aggressive course and worse prognosis. It is therefore possible (though by no means certain) that prolonged periods of low oxygen levels may help certain cancerous cells become more potent.
More research needs to be done before we can say with certainty that obstructive sleep apnea indeed puts people at a higher risk for cancer. But one thing is sure: if someone you know chokes and gasps at night, they should be evaluated by a physician for possible obstructive sleep apnea. There are already more than enough good reasons to treat it.
Dennis Rosen, M.D.
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Successful Sleep Strategies for Kids (a Harvard Medical School Guide)