%0 Case Reports %T Tegafur-uracil-induced pericardial effusion during adjuvant chemotherapy for resected lung adenocarcinoma: A case report. %A Kawamoto N %A Okita R %A Hayashi M %A Okada M %A Inokawa H %J Thorac Cancer %V 12 %N 5 %D 03 2021 %M 33463035 %F 3.223 %R 10.1111/1759-7714.13840 %X In Japan, oral administration of tegafur-uracil is recommended as postoperative adjuvant chemotherapy for patients diagnosed with primary lung adenocarcinomas of >2 cm size and staged as IA, IB, and IIA. Reports on chemotherapy-induced pericardial effusion are rare. Herein, we report a rare case of tegafur-uracil-induced pericardial effusion during postoperative adjuvant chemotherapy for primary lung cancer. A 60-year-old man underwent left lower lobectomy and mediastinal lymph node dissection for left lower lung adenocarcinoma. Lung cancer was staged as IB, and tegafur-uracil was administered as postoperative adjuvant chemotherapy from 1 month after the surgery. A computed tomography (CT) scan revealed a pericardial effusion 5 months after the surgery. A malignant pericardial effusion was suspected, and tegafur-uracil was discontinued. Pericardiocentesis could not be performed owing to a small amount of pericardial effusion. An 18 F-fluorodeoxyglucose (FDG) positron emission tomography/CT scan revealed no abnormal FDG uptake. During a short follow-up period after discontinuation of tegafur-uracil, a CT scan revealed a decrease in pericardial effusion, suggesting that the pericardial effusion was induced by tegafur-uracil. Follow-up of pericardial effusion is required while administering tegafur-uracil. In cases of pericardial effusion without symptoms and no suspicious metastatic lesions in other organs, we should be concerned about tegafur-uracil-induced pericardial effusion.