Rationale: Sleep-disordered breathing (SDB) has been associated with total and cardiovascular mortality, but an association with cancer mortality has not been studied. Results from in vitro and animal studies suggest that intermittent hypoxia promotes cancer tumor growth.
Objectives: The goal of the present study was to examine whether SDB is associated with cancer mortality in a community-based sample.
Methods: We used 22-year mortality follow-up data from the Wisconsin Sleep Cohort sample (n = 1,522). SDB was assessed at baseline with full polysomnography. SDB was categorized using the apnea-hypopnea index (AHI) and the hypoxemia index (percent sleep time below 90% oxyhemoglobin saturation). The hazards of cancer mortality across levels of SDB severity were compared using crude and multivariate analyses.
Measurements and main results: Adjusting for age, sex, body mass index, and smoking, SDB was associated with total and cancer mortality in a dose-response fashion. Compared with normal subjects, the adjusted relative hazards of cancer mortality were 1.1 (95% confidence interval [CI], 0.5-2.7) for mild SDB (AHI, 5-14.9), 2.0 (95% CI, 0.7-5.5) for moderate SDB (AHI, 15-29.9), and 4.8 (95% CI, 1.7-13.2) for severe SDB (AHI ≥ 30) (P-trend = 0.0052). For categories of increasing severity of the hypoxemia index, the corresponding relative hazards were 1.6 (95% CI, 0.6-4.4), 2.9 (95% CI, 0.9-9.8), and 8.6 (95% CI, 2.6-28.7).
Conclusions: Our study suggests that baseline SDB is associated with increased cancer mortality in a community-based sample. Future studies that replicate our findings and look at the association between sleep apnea and survival after cancer diagnosis are needed.