Pulmonary toxicity by a cytotoxic agent, S-1

A 72-year-old man with tongue carcinoma complained of dyspnea on exertion 18 days after starting treatment with S-1. Chest radiograph and CT scan suggested diffuse interstitial lesions with ground glass opacity on both lungs. Bronchoalveolar lavage and transbronchial lung biopsy revealed moderate lymphocyte infiltration with granuloma. Drug lymphocyte stimulation test was positive against tegafur, one of the components of S-1. These findings were consistent with S-1-induced lung injury. Both his symptoms and the radiographic findings were resolved dramatically after high-dose corticosteroid therapy. Clinicians should be aware that S-1 has the potential to cause lung injury when it is included in chemotherapy.