Some studies have identified links between sleep apnea and cancer. Now, new research reveals that rates of cancer are higher among females with pronounced symptoms of apnea.
The study, published in the European Respiratory Journal, analyzed data on 20,000 adults in the European Sleep Apnoea Database, a multinational study in which sleep laboratories recruit patients with suspected OSA. About 2% of the participants also had a diagnosis of cancer in their medical history.
A person with obstructive sleep apnea (OSA) experiences short and repeated interruptions of breathing while asleep because the throat muscles can’t keep the airway open. Another form of apnea, central sleep apnea, occurs due to a failure in brain signaling. Of the two types, OSA is by far the most common, affecting 5% to 20% of adults in the United States.
OSA can cause disturbed, fragmented sleep and lead to an insufficiency of oxygen. The combination of low oxygen and sleep disruption can give rise to high blood pressure, heart disease, memory problems, and mood disturbance.
Scientists have proposed several theories for a link between OSA and cancer. One theory says the two conditions share risk factors, such as age and obesity. Another theory is that intermittent hypoxia and sleep fragmentation may also explain the link to cancer, involving changes in the development of blood vessels, immune function, and the tissue environment of tumors.
The researchers found, as expected, an association between older age and a higher risk of cancer. After adjusting for age, sex, body mass index, alcohol intake, and smoking, they found a possible association between intermittent nocturnal hypoxia and higher rates of cancer. Their analysis also revealed that the risk of cancer was two to three times higher in females with severe symptoms of sleep apnea.
One of the investigators, Ludger Grote, an adjunct professor and chief physician in sleep medicine at Gothenburg University in Sweden, suggests that the combination of female sex hormones and stress arising from nocturnal hypoxia in OSA triggers the start of cancer or reduces the body's immune defenses. "It's reasonable to assume that sleep apnea is a risk factor for cancer or that both conditions have common risk factors, such as [being] overweight." However, he adds, "it is less likely that cancer leads to sleep apnea."
Source: medicalnewstoday.com, Aug. 19, 2019