목적: Radiation-induced inflammatory reactions—especially in the laryngopharyngeal regions—is a rare, but devastating complication in head and neck cancer patients after radiation therapy. Even after complete eradication of tumor cells, radiation reactions can adversely affect patients’ quality of life and potential survival outcomes. This study aimed to identify possible risk factors of radiation reactions particularly in laryngopharyngeal cancer patients. 방법:Patients diagnosed with hypopharyngeal or laryngeal cancer at this tertiary referral center from January 2011 to December 2020 were included in this study. Patients who received initial treatment other than radiation and those who received previous radiation therapy to the head and neck region for other diseases (e.g. esophageal cancer) were excluded. Diagnosis of radiation reaction was made when patients required admission due to radiation-induced change detected via either laryngoscopic or radiologic evaluation (Chandler grade III or IV). Possible risk factors were analyzed with Chi-square test with clinical significance determined with a p-value < 0.05. 결과:A total of 231 patients were enrolled in this study, and 14 patients (6.1%) were diagnosed with radiation reaction. Anterior commissure involvement was present in 69 patients, with 9 diagnosed with radiation reaction. Thyroid cartilage inner perichondrium involvement was present in 36 patients, with 7 being diagnosed with radiation reaction. Chi-square test revealed that anterior commissure involvement (OR 3.90 [1.33 – 11.43], p = 0.008), and thyroid cartilage inner perichondrium involvement (OR 5.64 [1.90 – 16.73], p < 0.001) were both significantly correlated with the occurrence of radiation reactions. Eighty-four out of the 231 patients were diagnosed with higher clinical T stage (T3/4) and 12 eventually developed radiation reaction, being significantly correlated (OR 8.00 [2.19 – 29.25], p < 0.001). Hyperbaric oxygen therapy (HBO) and intravenous antibiotics were employed in all radiation reaction patients, and one patient underwent total laryngectomy due to lack of response to either treatment. The mean overall survival time for radiation reaction group and the rest were 104.01 ± 14.47 months and 79.6 ± 2.52 months respectively, with no significant difference (p = 0.77). 결론:Radiation inflammatory reaction is a rare phenomenon, though must be suspected when laryngopharyngeal cancer patients who originally exhibited anterior commissure involvement, thyroid cartilage inner perichondrium involvement, or high clinical T stage. When diagnosed, empirical hyperbaric oxygen therapy and intravenous antibiotics can be applied to radiation reaction patients.