Impact of obstructive sleep apnea on cancer risk: a systematic review and meta-analysis

Purpose We aimed to study the effect of obstructive sleep apnea (OSA) on cancer risk. Methods We searched PubMed, Embase, and Cochrane databases for relevant studies. The qualities of included studies were assessed using Newcastle-Ottawa Scale (NOS). Unadjusted and adjusted analyses were performed. We also conducted subgroup analyses stratified by gender, severity of OSA, study design, and cancer type. Results After literatures search, 18 studies were included in the present study. In the unadjusted analysis, we discovered an increased cancer risk in patients with OSA with a pooled relative risk (RR) in the OSA group of 1.49 (95% confidence interval (CI): 1.32-1.69, I-2 = 32%, P = 0.15). In adjusted analysis, OSA correlated with cancer risk (RR: 1.36, 95% CI: 1.18-1.56, I-2 = 54%, P < 0.01). In subgroup stratified by gender and OSA severity, OSA statistically with cancer risk in females (RR: 1.27, 95% CI: 1.06-1.51) and moderate to severe OSA groups (RR: 2.62, 95% CI: 1.64; 4.19). In subgroup stratified by study design, a trend toward statistically significant differences was observed in prospective studies (RR: 1.21, 95% CI: 0.99-1.48) and cross-sectional studies (RR: 1.81, 95% CI: 0.96-3.41). Patients with OSA in the retrospective study group had a statistically higher chance of developing cancer (RR: 1.41, 95% CI: 1.11-1.79). When stratified by cancer group, statistically significant differences was observed in many types of cancer (breast cancer: RR: 1.32, 95% CI: 1.03-1.70; central nervous system cancer: RR: 1.71, 95% CI: 1.06-2.75; kidney cancer: RR: 1.81, 95% CI: 1.20-2.74; liver cancer: RR: 1.19, 95% CI: 1.10-1.29; and pancreatic cancer: RR: 1.23, 95% CI: 1.14-1.33). Conclusions This systematic review and meta-analysis suggests that obstructive sleep apnea may increase risk of cancer.