Zhao et al. (27) also showed that compared with those with negative PD-L1 expression, NSCLC patients with positive PD-L1 expression had significantly higher rates of lymph node metastasis (64.9% vs. 27.5%, p<0.01), more advanced tumor stage (p<0.01) and Ki-67 index (P<0.01), and thus concluded that positive PD-L1 expression was associated with more aggressive pathological features and poorer prognosis in advanced-stage NSCLC. This evidence concerns the gene MKI67 and metastatic malignant neoplasm in the lymph nodes.