The diagnostic process of non-small cell lung cancer (NSCLC) requires the help of effective biomarkers. It had been demonstrated that isocitrate dehydrogenase 1 (IDH1) was significantly increased in NSCLC tumors. Building on this, researchers conducted a further study in which they evaluated the validity of IDH1 levels in the diagnosis of NSCLC by examining blood IDH1 levels in a large patient population. The researchers obtained blood IDH1, CA125, Cyfra21-1 and CEA levels by ELISA. Study blood samples were obtained from 1,422 participants (943 NSCLC patients and 479 healthy controls). Samples were randomly assigned to a training set versus a test set. The diagnostic effects were evaluated by subject characteristics and dichotomous logistic regression analysis, and the associated diagnostic mathematical models were developed. It was found that blood IDH1 levels were significantly higher in NSCLC patients compared to healthy controls. The diagnosis of lung adenocarcinoma with the help of IDH1 was significantly better than that of CA125, Cyfra21-1 or CEA, and the model combining IDH1, CEA, CA125 and Cyfra21-1 could be used more effectively for the diagnosis of lung adenocarcinoma than the model using IDH1 alone. In addition IDH1 could also be useful in a diagnostic model for lung squamous cell carcinoma. Professor Herr et al. ultimately concluded that IDH1 could be used as a blood biomarker for the diagnosis of NSCLC, especially lung adenocarcinoma, given the relatively high sensitivity and specificity of IDH1.