OSA1An important new finding has come from an observational study linking obstructive sleep apnea with cancer mortality. Based on 22 years of follow-up data from the Wisconsin Sleep Cohort, investigators reported that mortality was higher for people with mild obstructive sleep apnea , moderate obstructive sleep apnea , and severe obstructive sleep apnea .

Cancer mortality in this context refers to all types of cancer, with lung cancer the most frequent. The researchers cited preclinical studies showing that chronic or intermittent hypoxia—the latter mimicking clinical obstructive sleep apnea—can lead to tumor growth and resistance to radiotherapy. This new research provides a possible mechanistic link between obesity and cancer, and will help to increase awareness of obstructive sleep apnea by broadening its potential detrimental outcomes beyond the cardiovascular system. Whether the purported effects of obstructive sleep apnea on cancer mortality will be reported in other cohorts or can be mitigated by intervention is unclear.

Treatment of patients with severe, symptomatic obstructive sleep apnea with continuous positive airway pressure (CPAP) is associated with a reduction in right atrial and ventricular size and left ventricular mass as measured by cardiac MRI and trans-thoracic echocardiography. However, use of CPAP might be associated with improved health behaviors—i.e., diet, exercise, adherence to drugs—rather than improved cardiovascular risk.

Researchers reported that patients with mild or moderate obstructive sleep apnea who were assigned to CPAP had a greater improvement in subjective functional capacity after 8 weeks than did patients given placebo Study of patients with asymptomatic obstructive sleep apnea randomly assigned to 6 months of CPAP or usual care noted a significant difference between groups in the change in daytime sleepiness.

Accumulating evidence of the detrimental outcomes of obstructive sleep apnea—in terms of sleepiness, cardiovascular and metabolic disease, and now possibly cancer—coupled with little improvement in objective outcomes in randomized controlled trials, suggests that the effects of obstructive sleep apnea are at least partly irreversible; or the first-line treatment—CPAP—might be only partly effective because of varying degrees of adherence.

If the effects of obstructive sleep apnea are shown to be irreversible, studies should focus on identification of young patients with less developed disease while also trying to curb reversible risk factors, most notably obesity.

These results show the multi-factorial nature of the pathogenesis of obstructive sleep apnea, which is often primarily attributed to the mechanical effects of obesity. One potential treatment option addressing a different cause of obstructive sleep apnea is implantable hypoglossal nerve stimulation, which has been substantially refined and tested. [Source &Courtesy: TheLancet.Com]

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Filed under: Cardiovascular DiseaseClinical ResearchCPAPCPAP TherapyDaytime SleepinessMetabolic SyndromeObesityObstructive Sleep ApneaOther DisordersSleepSleep ApneaSleep Apnea EffectsSleep Apnea ResearchSleep Apnea TreatmentSleep DisordersSleep Problems

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