Obstructive sleep apnea promotes cancer development and progression: a concise review. 
Obstructive sleep apnoea-hypopnoea (OSA) is an increasingly common sleep disorder which is widely accepted to be associated with high rates of morbidity and mortality.  OSA is an independent risk factor for cardiovascular diseases, cerebrovascular disease, and metabolic disease.  Recently, several studies have demonstrated that patients with OSA have a higher prevalence of cancer and cancer-related mortality.  The epidemiological surveys suggest that patients with OSA had a higher incidence of cancer and cancer-related mortality than patients without OSA.  Animal studies indicate that the activation of HIF-1 and VEGF pathways in response to intermittent hypoxia may promote the blood supply which supports tumor growth.  In addition, tumor-associated macrophages may be altered by intermittent hypoxia (or sleep fragmentation) to a tumor-promoting phenotype yielding more aggressive cancer behavior.  The relationship between OSA and cancer has been confirmed, in which patients with OSA have a relative high prevalence of cancer and cancer-related mortality.  The mechanism of OSA promoting cancer development and progression may be related with intermittent hypoxia and possibly sleep fragmentation.  The activation of several cancer-related pathways may play an important role in tumor growth and metastasis.  More clinical data and basic studies are needed to explain and confirm the relationship between OSA and cancer.