Obstructive sleep apnea and incident cancer: a large retrospective multicenter clinical cohort study

Background — To examine the association between the severity of obstructive sleep apnea (OSA) and nocturnal hypoxemia with incident cancer.

Methods — 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, 23% with severe OSA (apnea-hypopnea index >30). Of the 18,458 individuals with information on sleep time spent with oxygen saturation (SaO2) <90%, 5% spent >30% of sleep with SaO2<90% (severe nocturnal hypoxemia). Over a median of 7 years, 2,498/33,711 (7%) of individuals developed cancer with an incidence rate of 10.3 (10.0-10.8) per 1000 person-years. Controlling for confounders, severe OSA was associated with a 15% increased hazard of developing cancer compared to no OSA (HR=1.15; 1.02-1.30; ARD=1.28%; 0.20-2.37; 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; NNH=42).

Conclusions — In a large cohort of individuals with suspected OSA free of cancer at baseline, the severity of OSA and nocturnal hypoxemia were independently associated with incident cancer. 

Impact — Findings suggest the need for more targeted cancer risk awareness in individuals with OSA.