Chest malignant solid tumor (mainly lung and esophageal cancer) is a common malignant tumor that seriously threatens the health of residents in China. Its morbidity and mortality rank first,sixth,first,and fourth among all malignant tumors respectively. The treatment effect is not satisfactory,and the overall 5-year survival rate after surgery alone is about 20%-35%. Recent studies have shown that neoadjuvant therapy combined with surgery in the treatment of locally advanced esophageal cancer and lung cancer can significantly improve the efficacy compared with surgery alone. The results of multiple international and multi-center neoadjuvant immunotherapy showed that this new model of combined immunoadjuvant immunotherapy brought a breakthrough point for the treatment of malignant solid tumors of the chest. However,its safety and target benefit groups are still the biggest problems,and there is a large room for improvement. To develop the optimal treatment strategy,it is necessary to further clarify the immunomodulatory mechanisms of neoadjuvant CTIO,explore and develop new evaluation methods and prognostic biomarkers for the selection of targeted benefit patients,and the evaluation of efficacy. This is a key scientific issue in the current neoadjuvant CTIO treatment mode for thoracic malignant solid tumors,mainly lung and esophageal squamous cell carcinoma,which urgently needs to solve its safety and select the benefit population.