Sept. 6, 2022 – People who have obstructive sleep apnea could have increased risks for cancer, dementia, and dangerous blood clots, according to new studies presented Monday at the European Respiratory Society’s 2022 International Congress in Barcelona.

Patients with obstructive sleep apnea, or OSA, have part or all of their airways blocked during sleep, which interrupts breathing several times per night. This can lead to loud snoring, gasping, and daytime fatigue. The sleep disorder affects 7% to 13% of people, with the highest risks seen among those who are overweight or obese, have diabetes, smoke, or drink a lot of alcohol.

“It is known already that patients with obstructive sleep apnea have an increased risk of cancer, but it has not been clear whether or not this is due to the OSA itself or to related risk factors for cancer, such as obesity, cardiometabolic disease and lifestyle factors,” Andreas Palm, MD, a researcher and senior consultant at Uppsala University in Sweden, who presented one of the studies, said in a statement.

“Our findings show that oxygen deprivation due to OSA is independently associated with cancer,” he said.

Palm and colleagues looked at data from nearly 63,000 patients about 5 years before they started treatment for obstructive sleep apnea in Sweden. Between 2010 and 2018, patients were treated with continuous positive airway pressure, which keeps the airways open during sleep. The researchers linked this information with data from the Swedish National Cancer Registry and social and economic data from Statistics Sweden.

The research team matched about 2,000 patients with sleep apnea and a cancer diagnosis with a control group of 2,000 patients with sleep apnea but no cancer. They found that patients with cancer had more severe sleep apnea, and oxygen levels were lower in patients with lung cancer, prostate cancer, and melanoma.

“The findings in this study highlight the need to consider untreated sleep apnea as a risk factor for cancer and for doctors to be aware of the possibility of cancer when treating patients with OSA,” the researchers said. “However, extending screening for cancer to all OSA patients is not justified or recommended by our study results.”

In another study presented at the conference, obstructive sleep apnea was also linked to a greater decline in mental powers, particularly among men and people ages 74 and older.

Researchers in Switzerland studied 350 people who were 65 and older, took sleep tests between 2003 and 2008, and had follow-up appointments every 5 years. Cognitive assessments took place during the first follow-up between 2009 and 2013, as well as 5 years later, which tested for brain function, processing speed, executive function, verbal memory, language, and visual perception of spatial relationships between objects.

The research team found that obstructive sleep apnea was linked with a greater decline in brain function, processing speed, executive function, and verbal memory. Low oxygen levels during sleep had the greatest effects.

“This study demonstrates that the severity of sleep apnea and night-time oxygen deprivation contribute to cognitive decline in old age,” Nicola Marchi, MD, a researcher at the Centre for Investigation and Research on Sleep at Lausanne University in Switzerland, said during the presentation.

In a third study done in France, patients with severe obstructive sleep apnea were more likely to have venous thromboembolism, or dangerous blood clots that form in the lower leg, thigh, or pelvis and can trigger heart attacks or strokes.

The researchers studied 7,355 patients who were followed for more than 6 years, including 104 who got clots. Those who spent more than 6% of their sleep time with oxygen levels below 90% were 2 times more likely to get blood clots, as compared with patients who didn’t have oxygen deprivation.

“These three studies show worrying associations between obstructive sleep apnea and important diseases that affect survival and quality of life,” Winfried Randerath, MD, head of the European Respiratory Society’s Sleep Disordered Breathing Group and a professor at the University of Cologne in Germany, said in the statement.

“People should be made aware of these links and should try to make lifestyle changes in order to reduce their risk of OSA, for instance, by maintaining a healthy weight,” he said. “We look forward to further research that may help to clarify whether OSA may be causing some of the health problems seen in these studies.”

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European Respiratory Society International Congress 2022: “Oral presentation: Obstructive sleep apnea consequences and management.”

European Respiratory Society: “Obstructive sleep apnoea linked to increased risk of cancer, a decline in mental processing powers and an increased risk of blood clots.”

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