Use of oral glutamine in radiation-induced adverse effects in patients with thoracic and upper aerodigestive malignancies: Results of a prospective observational study

Cancer growth in host tissues features glutamine (gln) depletion over time, decreasing epithelial cells' optimal functioning. In addition, radiotherapy (RT) and/or chemotherapy (CT) cause damage to normal tissues, probably enhanced by this depletion. The present study prospectively examined the effect of gln supplementation on 72 patients with thoracic and upper aerodigestive malignancies (T&UAM) treated with sequential or concurrent RT-CT or RT alone. All patients received prophylactic gln powder 15 g bid for the full duration of treatment. The severity of acute radiation toxicities was graded according to the RT Oncology Group/European Organization for Research and Treatment of Cancer criteria. Primary endpoints were the incidence of grade >2 toxicities, weight loss and requirement for analgesics, and the secondary endpoint was the association of the length of irradiated esophagus from treatment planning with the use of opioids. The incidence of adverse effects was as follows: Grade >2 stomatitis, 25.0%; esophagitis, 60.5%; dysphagia, 54.2%; pain, 25.4%; mycosis, 40.8%. Stomatitis grade >2 was more frequent in patients with head and neck tumors (P<0.001) and in those with prior surgery (P<0.001). Esophagitis (P=0.020) and dysphagia (P=0.008) grade >2 were more frequent in patients with concurrent RT-CT. Regarding analgesics, 9.9% of patients received no pain treatment, 56.3% received simple analgesic therapy and 33.8% opioids. Patients on opioid therapy had a greater mean length of irradiated esophagus (P=0.024) or length >12 cm (P=0.018). In 54.2% of patients, weight loss was observed, particularly with concurrent RT-CT (P=0.007). Thus, the use of oral gln may have an important role in reducing acute radiation toxicities and weight loss, and in lowering the requirement for analgesics in patients with T&UAM. Further randomized trials are required to identify the appropriate gln dose, duration of treatment and precise radiation dosimetric parameters in this group of patients. The present clinical trial was retrospectively registered in the ClinicalTrials.gov Protocol Registration and Results System (registration no. NCT05054517/22-09-2021).