The goal of this study is to compare glutamine combined with thalidomide with glutamine in preventing radiation-induced oral mucositis. The aim of this study is to answer whether glutamine plus thalidomide could improve the median incidence time of grade 2 oral mucositis. Participants would be randomly divided into the two groups above mentioned.

Explore the therapeutic efficacy of glutamine combined with Thalidomide as compared to glutamine alone in preventing radiation-induced oral mucositis. The primary research endpoint is the median time to the onset of Grade II oral mucositis, defined as the number of days from the start of radiation therapy to the occurrence of Grade II oral mucositis.

Inclusion Criteria:

1. Age 18 to 75 years old;

2. Patients with locoregional advanced squamous cell carcinoma confirmed by pathological histology or cytology and requiring radiotherapy or concurrent chemoradiotherapy;

3. Patients who have received more than 45Gy of radiation in the oral area;

4. ECOG PS (Eastern Cooperative Oncology Group Performance Status) score of 0-1;

5. Basic hematological indicators are normal: White blood cell count ≥ 4×10^9/L; Absolute neutrophil count ≥ 1.5×10^9/L; Platelets ≥ 100×10^9/L; Hemoglobin ≥ 90 g/L;

6. Basic renal function is normal: Serum creatinine ≤ 1.5×ULN (Upper Limit of Normal) or Creatinine Clearance Rate (CrCl) > 60 mL/min (using the Cockcroft-Gault formula):

   For women: CrCl = (140 - age) × weight (kg) × 0.85 / (72 × Scr mg/dl) For men: CrCl = (140 - age) × weight (kg) × 1.00 / (72 × Scr mg/dl)

7. Basic liver function is normal: Serum total bilirubin ≤ 1.5×ULN; AST (Aspartate Aminotransferase) ≤ 2.5×ULN; ALT (Alanine Aminotransferase) ≤ 2.5×ULN.

8. Signed written informed consent.

Exclusion Criteria:

1. Participated in another interventional clinical trial within the last 30 days;
2. Patients with severe underlying oral diseases who cannot tolerate radiation therapy;
3. Patients allergic to glutamine and thalidomide;
4. Patients receiving secondary radiation therapy to the oral area;
5. Pregnant women (confirmed by blood or urine HCG testing) or breastfeeding women, or participants of childbearing age who are unwilling or unable to take effective contraceptive measures (applicable to both male and female participants) until at least 6 months after the last trial treatment;
6. Patients with underlying peripheral neuropathy;
7. Individuals deemed by the researcher to be inappropriate for participation in this study;
8. Unwilling to participate in this study or unable to sign informed consent.