Higher risk of cancer for women with sleep apnoea

Washington: A recent study finds that women who are deprived of sleep and suffer from obstructive sleep apnoea (OSA) are more likely to be diagnosed with cancer than men. The study was published in the journal, 'European Respiratory Journal'

OSA, where the airways close completely or partially many times during sleep, reduces the levels of oxygen in the blood, and common symptoms including snoring, disrupted sleep and feeling excessively tired.

The new research suggests that people who experience more closures of the airways during sleep and whose blood oxygen saturation levels drop below 90 per cent more frequently are more likely to be diagnosed with cancer than people without OSA.

It was also found that cancer was more prevalent among women with OSA than men, even after factors such as age; body Mass-Index (BMI), smoking status and alcohol consumption were taken into account, suggesting women with OSA may be at greater risk of being diagnosed with cancer than men with OSA.

Athanasia Pataka, study's lead researcher explained, "Recent studies have shown that low blood oxygen levels during the night and disrupted sleep, are both common symptoms in OSA, which may play an important role in the biology of different types of cancers."

But this area of research is very new, and the effects of gender on the link between OSA and cancer have not been studied in detail before, Pataka said.

The study analysed data from 19,556 people included in the European Sleep Apnoea Database (ESADA), an international multi-centre study that includes patients with OSA, to explore the link between OSA severity, low blood oxygen levels and cancer development.

The participants included 5,789 women and 13,767 men in total, who were also assessed for their age, BMI, smoking status and level of alcohol use, as these factors can impact the risk of developing cancer.

Professor Pataka explained their results: "Our study of more than 19,000 people shows that the severity of OSA is linked to a cancer diagnosis. This link was especially strong in the women that we analysed, and less so in the men, and suggests that severe OSA could be an indicator for cancer in women, though more research is needed to confirm these findings."

The study did not explicitly explore the causes of different cancers, but cancer may differ between men and women because of factors such as how hormones affect tumour growth.

"How the different types of cancer that were more prevalent in men and women are affected by low blood oxygen levels; or how gender-specific exposure to cigarette smoking may play a role," she added.

The classic symptoms of OSA such as sleepiness, snoring and stopping breathing during the night time are reported more frequently in men, but other lesser known symptoms like fatigue, insomnia, depression and morning headaches are more common in women, "therefore clinicians should be more careful when evaluating their female patients for possible OSA," Pataka said.

The researchers note that their analysis did not account for other factors that may affect cancer risks, such as participants' physical activity, marital status, education level and occupation, which potentially limits the study.

They also stressed that their results cannot show that OSA causes the increased risk of cancer, only that there is an association between the two, and say that further research is needed to understand how OSA symptoms and treatment may affect cancer.

The research team plan to conduct a follow-up study to evaluate the number of cancer diagnoses and cancer deaths in the ESADA population with OSA, and even to look at specific cancers in more detail and how OSA treatment may affect outcomes.