['The purpose of this study was to assess the the efficacy of oral glutamine (GLN) in prevention of acute radiation-induced esophagitis in patients with lung cancer and determine the predictive role of clinical and dosimetric parameters.', 'Thirty-two patients diagnosed with lung cancer were studied prospectively. Sixteen patients (50%) received prophylactic powdered GLN orally in doses of 10g/8h. Patients were treated 2 Gy per fraction daily, 5 days a week. We evaluated the grading of esophagitis daily at the end of each fraction of each treatment day until a cumulative dose of 50 Gy was reached. The primary end point was radiation-induced esophagitis.', 'All patients tolerated GLN well. Toxicity grade, weight loss, serum cytokine levels and esophageal transit times exhibited statistically significant improvement in the GLN receiving group. GLN suppressed the inflammation related to the disease and treatment and reduced toxicity with statistical significance.'] Does oral glutamine supplementation reduce radiotherapy- induced esophagitis in lung cancer patients?