Sleep Apnea Could Increase Risk Of Cancer, Says Study

One in 20 people in Britain currently suffer from sleep apnea - the sleeping disorder where a person temporarily stops breathing because their throat closes repeatedly while they sleep.

Obstructive sleep apnea, (OSA), can lead to heavy snoring and tiredness during the day and now the condition has also been linked to cancer.

Reported in the April 15 issue of the Journal of Clinical Sleep Medicine, researchers at the University of Sydney Nursing School in Australia found that people with moderate-to-severe OSA may be two and a half times more likely to develop cancer.

Cancer mortality was found to be over three times (3.4) more common in those with sleep apnea than with no sleep apnea during a 20 year follow-up.

This is not the first study to link sleep apnea with cancer - an earlier study from Wisconsin showed the risk of dying with cancer doubled with moderate OSA and was 4.8 times higher with severe OSA. A Spanish study also showed elevated cancer incidence as well.

All three analyses were spurred by mouse model findings suggesting that deficiency of oxygen reaching the tissue spurred more rapid tumor growth.

The Australian study, led by Nathaniel Marshall, assessed 397 men and women from 1990 using a portable home sleep testing device.

The study also showed moderate-to-severe sleep apnea to increase the risk of stroke.

Richard Kim, MD, and Vishesh K. Kapur, MD, MPH, both of the University of Washington in Seattle, have said that more research into OSA is needed.

"In the Bradford Hill criteria for assessing causality, an important factor is whether the association has 'been repeatedly observed by different persons, in different places, circumstances and times," Kim and Kapur wrote.

"Additional long-term longitudinal studies which include objective assessment of OSA, more extensive ascertainment of important confounders, and detailed cancer outcomes are needed," they added. "Indeed, a variety of study types, including mechanistic and interventional studies, would help more fully ascertain whether a causal relationship between OSA and cancer exists."