In 2012, two studies found a correlation between sleep apnea and cancer. At the time of their publication, the New York Times reported that these were the first studies to find this connection. Though there were still some doubts about the validity of this relationship, sleep medicine experts noted that it was better to have sleep apnea diagnosed and treated than take the risk.

Now, a new study is contradicting the findings of the 2012 studies. Published in the Canadian Medical Association Journal, the new study found that the relationship between sleep apnea and incidence of cancer does not exist independent of other factors. The research team controlled for a number of other participant characteristics, including a diagnosis of chronic obstructive pulmonary disease (COPD), waist circumference, age, sex, body mass index, and smoking status.

After controlling these characteristics, which included known risk factors for cancer, there is no relationship between sleep apnea and cancer incidence. The U.S. News and World Report Health cautions that this study does not confirm or deny previous explanations of how sleep apnea causes cancer. Those explanations point to the intermittent lack of oxygen, causing chronic hypoxemia, as the reason for carcinogenesis.

Sleep apnea is a common disorder that causes snoring, fatigue, and dangerous pauses in breathing at night. About 28 million Americans have some form of sleep apnea, though many cases go undiagnosed. For sleep doctors, the condition is a top concern because it deprives the body of oxygen at night and often coincides with cardiovascular disease, obesity, and diabetes. Experts will continue to debate whether or not it also coincides with cancer.