Several recent studies have demonstrated an increased risk of premature death in those with sleep apnea, implicating several different possible reasons. Cancer and cardiovascular effects have been among the leading candidates.
In this month’s issue of the Journal of Clinical Sleep Medicine, another paper once again points out this relationship. The report is a 20-year follow-up of all causes of mortality in 400 residents in the Western Australian town of Busselton, making it part of the Busselton Health Study Cohort done at the University of Sydney.
The researchers found that moderate and severe sleep apnea (meaning more than 15 respiratory obstructions per hour) was associated with a higher incidence of cancer and cancer-related deaths. In fact, people with moderate or severe sleep apnea were 2.5 times as likely to get cancer, and 3.4 times as likely to die from cancer. Mild sleep apnea did not impact cancer risk.
Two other recent studies have related cancer incidence and death to sleep apnea. In one, researchers found the growth rate of melanoma cells was accelerated by sleep apnea. Another found that mild sleep apnea resulted in a 10 percent increased risk of death, and that moderate and severe sleep apnea led to a two-fold and five-fold increased death risk, respectively.
We estimate that 18 million Americans have sleep apnea. Of those, only about 20 percent have been diagnosed and treated. As a result, sleep apnea is of major public health significance. There have been a few encouraging studies demonstrating that with treatment, the risk of cancer decreases. In one, effective treatment was associated with positive changes in cancer-related genetic pathways, according to a white blood cell analysis.
We have begun to realize which specific sleep apnea factors may encourage tumor growth. The most likely factor is the low oxygen that results from repeated respiratory obstructions. We believe this encourages new blood vessel growth (neovascularization), which ends up feeding the tumor cells and promoting their growth. Genetic changes that result from sleep apnea may also be to blame.
We need to take this disorder very seriously. The incidence of sleep apnea is increasing, in great part due to our love of fast food, sugary drinks, and the resulting epidemic of obesity, which predisposes many of us to the disorder. Therefore, as if we did not already have enough reasons to treat sleep apnea, we can now add cancer. Here are easy signs of sleep apnea to look out for: loud snoring, daytime fatigue, interrupted breathing, or large neck (men 17” and women 16”). If you or a loved one has any of these, get it checked out. I think that before long we will be adding “check for sleep apnea” to such things as a colonoscopy and breast or prostate exams.