Obstructive sleep apnea and long-term risk of site-specific cancers: A population-based cohort study.

BACKGROUND: Obstructive sleep apnea is common, but its long-term association with site-specific cancers remains unclear. In this study, we examined 15-year risks of site-specific cancers in people with obstructive sleep apnea compared with the general population and to people with overweight or obesity. METHODS: We conducted a nationwide population-based cohort study using Danish registries, 1995-2021. People diagnosed with obstructive sleep apnea were compared with the general population and to people with overweight or obesity. Adjusted (weighted) 15-year risks, risk differences, and risk ratios (RRs) were estimated using the Aalen-Johansen estimator. Confounding was addressed using standardized morbidity ratio weighting. RESULTS: The study included 114,264 people with obstructive sleep apnea, 115,497 members of the general population, and 113,034 with overweight or obesity. After weighting, the distributions of sex (74% male), age (median 53 years), and comorbidities were comparable across the three cohorts. Obstructive sleep apnea was associated with an increased risk of cancers of the brain (adjusted 15-year risk: 5.78 vs. 3.61 per 1,000 persons; aRR 1.60 [95% CI 1.43-1.78]) and spinal cord (1.65 vs. 1.17 per 1,000 persons; aRR 1.41 [95% CI 1.16-1.72]) compared with the general population. Associations persisted when the obstructive sleep apnea cohort was compared with those with overweight or obesity. No associations were observed for other site-specific cancers. CONCLUSION: Obstructive sleep apnea was associated with an increased risk of brain and spinal cord cancers. These findings highlight the importance of effective prevention of obstructive sleep apnea and the need for further research on treatment.