Purpose/Objective(s): Whether oral glutamine help alleviate radiotherapy (RT)–induced toxicity remains controversial. We aim to explore the association between oral glutamine and acute toxicities in patients with head and neck cancer under RT.

Materials/Methods: This is a parallel, double-blind, randomized, placebo-controlled phase III trial conducted in one university hospital. A central randomization center used computer generated tables to allocate intervention for 71 patients with stage I-IV head and neck cancer. We excluded patients with diabetes mellitus, renal or hepatic insufficiency, history of prior irradiation or sepsis, distant metastasis, or with Eastern Cooperative Oncology Group (ECOG) performance status scoring larger than 2. The oral mucosa and the neck skin at baseline were healthy in all patients. The patients, care providers, and investigators were blinded to group assignment. Eligible patients received either oral glutamine (5g glutamine and 10g maltodextrin) or placebo (15g maltodextrin) 3 times daily during the period: 7 days before RT to 14 days after RT. The primary and secondary endpoints were radiation-induced oral mucositis and neck dermatitis, respectively. They were documented in agreement with the National Cancer Institute Common Terminology Criteria for Adverse Events version 3. Cox regression, log-rank test, and Kaplan–Meier curves were calculated.

Results: Seventy-one patients were randomized. We included 64 patients (placebo n=33; glutamine n=31) who completed RT for intention-to-treat (ITT) analysis. Five patients were excluded because of non-adherence, leaving 59 (placebo n=29; glutamine n=30) patients for per-protocol (PP) analysis. The use of glutamine, higher mean dose to the oral cavity, the incidence of opioid use and the decrease of body mass index (BMI) were significantly related to severe mucositis in the univariate ITT analysis. In multivariate analysis, glutamine had no significant effect on the severity of oral mucositis (OR 0.3, 95% CI 0.05-1.67; P =0.169). Only BMI change was significant in both multivariate ITT (OR 0.41, 95% CI 0.20-0.84; P =0.015) and PP analysis (OR 0.40, 95% CI 0.20-0.83; P =0.014) after adjusting baseline nutritional status and biochemical profile, primary tumor location and stage, severity of neck dermatitis, mean and maximum dose to the oral cavity, RT interruption days, PNI change during RT, performance status, operation, chemotherapy, alcohol or tobacco use history, betel nut chewing habits, the incidence of opioid use etc. No difference was found in the incidence and the severity of neck dermatitis between the 2 arms.

Conclusion: The decrease of BMI during RT was an independent and stable factor for the severity of oral mucositis, but not the use of glutamine.