Interesting research has recently been published about the link between Obstructive Sleep Apnoea (OSA) and cancer.
The researchers’ findings are interesting because it marks the first time that cancer growth has been associated with sleep apnoea in people. In a previous study about a year ago, Spanish researchers had already linked the intermittent lack of oxygen present at night in people with OSA — known as hypoxia — with increased tumour growth in mice.
In one of the new studies, researchers at the University of Wisconsin School of Medicine and Public Health studied data on about 1,500 workers who had been having regular overnight sleep studies every four years since 1989.
The researchers found that people with severe sleep apnoea who had the most intermittent disordered breathing problems were almost five times more likely to die from cancer than those without OSA. They also found that people considered having moderate OSA died of cancer at double the rate than those without OSA.
This is consistent with the theory that an increase of disordered breathing contributes to cancer cell growth because the intermittent reduction in oxygen levels.
When OSA patients were being treated with continuous positive airway pressure (CPAP) therapy were removed from the study data, the results showed those who use CPAP to reduce the impact of their OSA may reduce their risk of dying from cancer due to OSA-related oxygen depletion.
In the second related study, researchers at the Spanish Sleep Network used an index that measures the amount of time the level of oxygen in a person’s blood drops below 90 percent at night.
The researchers followed more than 5,000 OSA patients for seven years. They found that those with the most severe forms of sleep apnoea had a 65 percent greater risk of developing cancer of any kind.
It should be noted that, in both the Wisconsin and Spanish studies, the researchers only looked at cancer diagnoses and deaths in general, not the specific type of cancer.
These studies add yet another area of impact of untreated OSA – beyond the better described effects such as those on blood pressure and daytime sleepiness. They give another important reason to have OSA excluded if there any suggestion of symptoms.