Some studies have identified links between sleep apnoea and cancer. Now, new research reveals that rates of cancer are higher among females with pronounced symptoms of apnoea.
The international research team points out that while the findings do not prove that sleep apnoea causes cancer, there appears to be a clear link in females.
“It’s reasonable to assume that sleep apnoea is a risk factor for cancer or that both conditions have common risk factors, such as being overweight,” says Ludger Grote, an adjunct professor and chief physician in sleep medicine at Gothenburg University in Sweden.
“On the other hand,” he adds, “it is less likely that cancer leads to sleep apnoea.”
“The condition of sleep apnoea is well-known to the general public and associated with snoring, daytime fatigue, and elevated risk of cardiovascular disease, especially in men,” Dr. Grote explains.
He and his colleagues note that while there is growing evidence for a link between OSA and cancer, it remains under debate. The main reason appears to be the small numbers of study participants and “poor characterization” of types of OSA and cancer.
Theories about cancer and sleep apnoea
Until the recent research, very few studies had examined whether biological sex made a difference to the link between OSA and cancer.
In their results, Dr Grote and his colleagues found, as expected, that there was an association between older age and a higher risk of cancer.
However, when they adjusted the results of the analysis to take out the potential influence of age, sex, body mass index (BMI), alcohol intake, and smoking, they found a possible association between intermittent nocturnal hypoxia and higher rates of cancer.
Stronger link in females
In addition, the analysis revealed that the link between nocturnal hypoxia and higher rates of cancer was stronger in females and weaker in males.
The results suggest that the risk of cancer is two to three times higher in females with severe symptoms of sleep apnoea.
Dr Grote says that previous research has tended to focus on the link between OSA and malignant melanoma. In the light of his team’s findings, “Cancer of the breast or womb may now become a new area,” he suggests.
Perhaps a combination of female sex hormones and stress arising from nocturnal hypoxia in OSA triggers the start of cancer or reduces the body’s immune defences, he muses.
“It’s impossible to say for sure what causes underlie the association between sleep apnoea and cancer, but the indication means we need to study it in more depth,” said Dr Ludger Grote.
Source: Medical News Today