CD274 and obstructive sleep apnea syndrome: Compared with patients with lung cancer without OSA, the percentage counts of monocytes positively expressing PD-L1 were markedly higher in serum samples from patients with lung carcinoma with concomitant OSA (95.3% vs. 86.0%), and this result was positively related to the parameters AHI and ODI, which reflected the severity of OSA (r=0.419 and 0.387, P<0.05, respectively) (90).