Effects of CKI for Oral Mucositis Caused by Radiotherapy for Head and Neck Cancer

Inclusion Criteria: 1. Patients are pathologically diagnosed as stage III or stage Ⅳ squamous cell carcinoma of head and neck cancer (including nasopharyngeal carcinoma)and are in accordance with the diagnostic criteria of radiotherapy induced mucositis/ stomatitis; 2. Patients have no prior history of radiotherapy, and grade III oropharyngeal mucositis occured after the first radiotherapy; 3. Patients have no stomatological diseases such as ulcer, edema and exudation in the oropharyngeal mucosa before radiotherapy; 4. Eastern Cooperative Oncology Group (ECOG) performance Score is 0 or 1; 5. The function of each organ is basically normal, including: hemoglobins ≥ 9g/dL, platelets ≥ 80×10\^9/L, leukocytes ≥ 3×10\^9/L, liver function within 3 times the upper normal limit, creatinine clearance ≥ 60mL/min; 6. Patients aged between 18 and 75 years; 7. Patients have a life expectancy of at least 6 months; 8. Patients have fully understood the study and signed the informed consent voluntarily prior to any related procedures of the study. Exclusion Criteria: 1. Patients who have received CoKS or systemic antibiotic treatment within 2 weeks before treatment; 2. Patients who have a history of head or neck surgery (except biopsy); 3. Female patients who are pregnant or breast feeding or female of pregnancy potential with a positive pregnancy test before treatment; 4. Patients with serious or uncontrolled organic diseases or infections, such as decompensate cardiac function failure, pulmonary function failure, liver function failure, renal function failure, causing unability to tolerate radiotherapy; 5. Patients who have radiotherapy contraindications; 6. Patients who are allergic to the study medications or quinolones; 7. Patients have serious psychological or psychiatric disorders, drug abuse or alcohol dependence in the past; 8. Patients are currently participating in another clinical study or have participated in another clinical trial in the past 30 days; 9. The investigator believes that it is not appropriate to participate in this trial.