Radiation myelitis after durvalumab administration following chemoradiotherapy for locally advanced non-small cell lung cancer: an illustrative case report and review of the literature Abstract A 69-year-old man with stage IIIB lung adenocarcinoma received durvalumab following chemoradiotherapy. The prescribed dose was 50 Gy in 2 Gy fractions, and the maximum spinal cord dose was 40 Gy. After three cycles of durvalumab, he experienced bladder and rectal disturbance, muscle weakness in the lower limbs, and sensory loss in the lower body. Magnetic resonance imaging revealed T2 signal hyperintensity involving the thoracic spinal cord. As the thoracic spinal cord with T2 signal hyperintensity matched with the irradiated site, the patient was diagnosed with radiation myelitis. This case report shows the clinical and radiographic features of a case of locally advanced non-small cell lung cancer that demonstrated radiation myelitis following durvalumab administration. The time of onset was very early and the influence of durvalumab was suspected as the cause of myelitis.