PDCD1 and non-small cell lung carcinoma: Nevertheless, ECOG performance status score (HR = 0.69, P=0.03) and number of metastatic lesions (HR = 0.61, P=0.02) were also statistically significant after multivariate analysis, suggesting that ECOG performance status and number of metastatic lesions were independent factors for predicting the PFS of PD-1 inhibitor monotherapy among elderly patients with advanced NSCLC.