Obstructive sleep apnea and the prevalence and incidence of cancer

Background: A link between obstructive sleep apnea and cancer development or progression has been suggested, possibly through chronic hypoxemia, but supporting evidence is limited. We examined the association between the severity of obstructive sleep apnea and prevalent and incident cancer, controlling for known risk factors for cancer development. Methods: We included all adults referred with possible obstructive sleep apnea who underwent a first diagnostic sleep study at a single large academic hospital between 1994 and 2010. We linked patient data with data from Ontario health administrative databases from 1991 to 2013. Cancer diagnosis was derived from the Ontario Cancer Registry. We assessed the cross-sectional association between obstructive sleep apnea and prevalent cancer at the time of the sleep study (baseline) using logistic regression analysis. Cox regression models were used to investigate the association between obstructive sleep apnea and incident cancer among patients free of cancer at baseline. Results: Of 10 149 patients who underwent a sleep study, 520 (5.1%) had a cancer diagnosis at baseline. Over a median follow-up of 7.8 years, 627 (6.5%) of the 9629 patients who were free of cancer at baseline had incident cancer. In multivariable regression models, the severity of sleep apnea was not significantly associated with either prevalent or incident cancer after adjustment for age, sex, body mass index and smoking status at baseline (apnea-hypopnea index > 30 v. < 5: adjusted odds ratio [OR] 0.96, 95% confidence interval [CI] 0.71-1.30, for prevalent cancer, and adjusted hazard ratio [HR] 1.02, 95% CI 0.80-1.31, for incident cancer; sleep time spent with oxygen saturation < 90%, per 10-minute increase: adjusted OR 1.01, 95% CI 1.00-1.03, for prevalent cancer, and adjusted HR 1.00, 95% CI 0.99-1.02, for incident cancer). Interpretation: In a large cohort, the severity of obstructive sleep apnea was not independently associated with either prevalent or incident cancer. Additional studies are needed to elucidate whether there is an independent association with specific types of cancer.