Abstract
BACKGROUND: To examine the association between the severity of obstructive sleep apnea (OSA) and nocturnal hypoxemia with incident cancer. METHODS: This was a multicenter retrospective clinical cohort study using linked clinical and provincial health administrative data on consecutive adults who underwent a diagnostic sleep study between 1994 and 2017 in four academic hospitals (Canada) who were free of cancer at baseline. Cancer status was derived from the Ontario Cancer Registry. Cox cause-specific regressions were utilized to address the objective and to calculate the 10-year absolute risk difference (ARD) in the marginal probability of incident cancer and the number needed to harm (NNH). RESULTS: Of 33,997 individuals considered, 33,711 with no missing OSA severity were included: median age, 50 years; 58% male; and 23% with severe OSA (apnea-hypopnea index >30). Of the 18,458 individuals with information on sleep time spent with oxygen saturation (SaO(2)) <90%, 5% spent >30% of sleep with SaO(2) <90% (severe nocturnal hypoxemia). Over a median of 7 years, 2,498 of 33,711 (7%) individuals developed cancer, with an incidence rate of 10.3 (10.0-10.8) per 1,000 person-years. Controlling for confounders, severe OSA was associated with a 15% increased hazard of developing cancer compared with no OSA (HR = 1.15, 1.02-1.30; ARD = 1.28%, 0.20-2.37; and NNH = 78). Severe hypoxemia was associated with about 30% increased hazard (HR = 1.32, 1.08-1.61; ARD = 2.38%, 0.47-4.31; and NNH = 42). CONCLUSIONS: In a large cohort of individuals with suspected OSA free of cancer at baseline, the severity of OSA and nocturnal hypoxemia was independently associated with incident cancer. IMPACT: These findings suggest the need for more targeted cancer risk awareness in individuals with OSA.