There is no link between sleep apnea and cancer, according to a recent Canadian study.

Sleep apnea is defined by repeated periods of disrupted breathing during sleep leading to lower oxygen levels. Previous studies have linked these low levels of oxygen to cell mutations that are connected with cancer.

However, this study, published in Canadian Medical Association Journal, found that researchers were unable to confirm the link between sleep apnea and cancer.

"We are not able to confirm previous hypotheses that obstructive sleep apnea is a cause of overall cancer development through intermittent lack of oxygen," said lead author Tetyana Kendzerska. 

She said more studies are needed to examine the effect of sleep apnea on specific cancer types.

There are a variety of risk factors for sleep apnea such as obesity, smoking and diabetes.

Kendzerska and her team examined over 10,000 patients with sleep apnea. At the beginning of the study, 5 percent of patients had cancer and after eight years, an additional 6.5 percent had developed cancer.

Although there was no link between sleep apnea and cancer in general, the researchers did find that the low oxygen levels from sleep apnea were related to smoking-related cancers such as lung cancer.

"The mechanisms are still unclear," Kendzerska said. "And those results obtained from subgroup analyses should be interpreted with caution."

The study did not confirm previous studies. The study was a larger study with a long follow up time, but the researchers did not have data about participant's cancer stage or management.

"The longitudinal evidence on this relationship is very limited, and one of four studies published before ours also reported a lack of association," Kendzerska said.

According to the National Heart, Lung, and Blood Institute defines sleep apnea as a common disorder characterized by pauses in breathing or shallow breaths during sleep.

Sleep apnea can go undiagnosed since doctors won't be able to confirm the condition during an office visit and no blood test can diagnose the condition. It can only been developed through a sleep study. Usually a family member will notice the signs of sleep apnea.

Sleep apnea can increase risk cardiovascular issues such as heart attack, stroke or arrhythmias. It requires long-term management.