This randomized study compared the incidence and severity of radiation esophagitis with folic acid and with conventional symptomatic treatment.

By prospective randomized controlled study, this study research plans to recruit with diagnosis of lung cancer patients, according to whether there is drug intervention were divided into treatment group and control group, compared two groups of acute radiation esophagitis in the before and after the intervention, extent of occurrence of folic acid and clinical curative effect, so as to verify whether folic acid can be used as an intervention in the treatment of radioactive esophagitis, To explore the safety of folic acid in the treatment of radioactive esophagitis and explore the standardized treatment of radioactive esophagitis.

Inclusion Criteria:

1. Patients with malignant lung cancer (incluedig Non-small cell lung cancer, small cell lung cancer) diagnosed by histopathology or cytology.
2. TNM Stage N2~N3 (IASLC International TNM staging standard for Lung Cancer, 8th edition) was indicated by radiotherapy and the patients were treated for the first time.
3. Aged between 18 and 75 years old,no limit on the gender.
4. ECOG≤2 or KPS≥70.
5. No contraindication of Concurrent chemoradiotherapy.
6. Patients without important organ dysfunction,hematology: it is within the normal range according to the standards of each laboratory; Cardiac function: normal range; Liver function: normal range; Renal function: normal range; Pulmonary function: FEV1 > 50%, mild to moderate impairment of pulmonary function.
7. Patients with good compliance to treatment received and follow-up.

Exclusion Criteria:

1. Prior to treatment, there were other esophageal diseases, such as gastrointestinal ulcer, reflux esophagitis, cardia relaxation.
2. Patients with severe nutritional anemia prior to treatment.
3. The IV stage patients with uncontrolled malignant pleural effusion,with diffuse liver or lung metastasis which lead to liver or pulmonary dysfunction.
4. Patients with severe heart, lung or kidney diseass,such as uncontrolled hypertension, diabetes, unstable angina, a history of myocardial infarction or heart failure, or uncontrolled arrhythmias; There is clearly clinically diagnosed heart valve disease; The active phase of a bacterial, fungal, or viral infection; Mental disorders; Severely impaired lung function.
5. A history of previous tumors complicated with other malignant tumors.
6. The pregnant or breast-feeding patients.
7. Patients with mental and neurological diseases.