It’s a well-known fact that snoring is one of the main symptoms of sleep disordered breathing (SDB). American scientists have recently conducted a research which has shown an association between SDB and cancer death.
Experts suppose that the link may be due to problems causing an inadequate supply of oxygen. The latest research from the University of Wisconsin-Madison in the US also points to a connection with cancer mortality, reports The Telegraph.
Laboratory studies confirmed that intermittent hypoxia – or oxygen starvation – may cause tumour growth in mice with skin cancer.
Lack of oxygen stimulates the generation of blood vessels that nourish tumours, a process also known as angiogenesis. SDB covers a range of disorders that lead to interrupted breathing during sleep.
By the way, the most common disorder is obstructive sleep apnoea, due to which the airway collapses, leaving the sleeper struggling for breath. Typically this produces snoring and repeated forced waking.
Sleep apnoea can be linked to such illnesses as obesity, diabetes, high blood pressure, heart attacks and strokes. The latest research from the University of Wisconsin-Madison in the US also points to a connection with cancer mortality.
During the research experts examined 22 years-worth of data on a total of 1,522 people who took part in a study of sleep problems. Participants underwent some tests such as measurements of sleep and breathing at four-year intervals.
The results showed an association with cancer death that increased sharply with SDB severity. People with mild SDB were just 0.1 times more likely to die from cancer than those without the problem. However, moderate SDB doubled the chances of cancer death, while severe SDB increased the risk 4.8 times.
The head of the research group, Dr Javier Nieto, from the University of Wisconsin School of Medicine and Public Health, explained: “The consistency of the evidence from the animal experiments and this new epidemiologic evidence in humans is highly compelling.”
He continued: “In vitro (laboratory) and animal studies suggest that intermittent hypoxia promotes angiogenesis and tumour growth, which can explain these observations.”
“Ours is the first study to show an association between SDB and an elevated risk of cancer mortality in a population-based sample. If the relationship between SDB and cancer mortality is validated in further studies, the diagnosis and treatment of SDB in patients with cancer might be indicated to prolong survival.”
The expert also suggested that “additional studies are needed to replicate our results and to examine the relationships between SDB, obesity, and cancer mortality.”
The results of the study were presented on Sunday at the annual conference of the American Thoracic Society in San Francisco. According to sources, they will also be published in the American Journal of Respiratory and Critical Care Medicine.
The scientists took into consideration age, sex, body mass index (BMI – a measurement relating height and weight), smoking and other factors that may have influenced the results. They were quite surprised to discover that the association was stronger for non-obese patients than obese patients.