<h4>Background</h4>This study analyzed the risk factors of radiation-induced oral mucositis (RIOM) for nasopharyngeal carcinoma (NPC) and the correlation between epidermal growth factor (EGF), soluble myeloid cell expression trigger receptor-1 (sTREM-1), and disease severity.<h4>Methods</h4>A total of 124 patients with NPC who received radiotherapy from March 2013 to November 2016 were enrolled and divided into the study group (n=68) and the control group (n=56) regarding the presence of RIOM. The gene discussed is EGF; the disease is oral mucositis.