There is no description of the accuracy of lung cancer triple test for cancer. Clinically, it is mainly described by sensitivity and specificity, which means that lung cancer triple test indicates that the patient has or does not have malignant tumor and that the patient does or does not have tumor, which are called true positive, false positive, true negative and false negative respectively. Regarding the accuracy of the three tests for lung cancer, the terms sensitivity and specificity are used statistically. Sensitivity is the percentage of true positives among positive test results, and specificity is the percentage of true negatives among negative test results. Carcinoembryonic antigen (CEA) in three lung cancer tests has a sensitivity of 87% in patients with non-small cell lung cancer, 58% for tumor recurrence, and about 10%-30% in small cell lung cancer. Cytokeratin 21-1 fragment (Cyfra21-1) has a sensitivity of 50%-65% and specificity of 96% in non-small cell lung cancer, and a sensitivity of 76.5% in squamous carcinoma compared to adenocarcinoma ( 47.8%) and small cell lung cancer (42.1%). Neuron-specific enolase (NSE) was 40%-70% sensitive and 65%-80% specific for small cell lung cancer, and NSE was increased in 40%-70% of small cell lung cancers in the limited stage and 83%-98% in the extensive stage.