Some studies have identified links between sleep apnea and cancer. Now, new research reveals that rates of cancer are higher among females with pronounced symptoms of apnea, Medical News Today reports.

The recent study, which features in the European Respiratory Journal, analyzed data on 20,000 adults with sleep apnea.

About 2% of the participants also had a diagnosis of cancer in their medical history.

The data came from the European Sleep Apnea Database (ESADA), which has medical and visit records on adults registered at 33 centers across Europe.

The international research team points out that while the findings do not prove that sleep apnea causes cancer, there appears to be a clear link in females.

"It's reasonable to assume that sleep apnea 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 apnea."