The following features were associated with etiology of cancer: age >40 years-old (RR=2.57; p=0.000); cigarette smoking (RR=1.73; p=0.030), hemoptysis (RR=2.66; p=0.000), dyspnea (RR=2.02; p=0.006), hoarseness (RR=2.14; p=0.009), superior vena cava syndrome (RR=2.29; p=0.004), lymph nodes with homogeneous density (RR=3.87; p=0.000), lymph nodes presented as one mass (RR=3.69; p=0.000), lymph nodes with lobular margin (RR=4.79; p=0.000); accompanied with pulmonary parenchymal abnormalities (RR=8.42; p=0.000).