Abstract: Small intestinal metastases from primary lung cancer are rare. Such patients have a poor prognosis. Early diagnosis of small intestinal metastases is difficult because of the low incidence of clinically apparent symptoms. The standard treatment for small intestinal metastases has not been established. A 69-year-old Chinese man presented for evaluation of a tumor in the right lower lung and mediastinal lymph node enlargement on clinical examination. The clinical stage was cT₂N₂M₀ (stage IIIA). Histologic examination of the tumor revealed lung adenocarcinoma. He could not tolerate surgery; hence, he received two chemotherapy regimens. However, the disease progressed. He had bloating after chemotherapy and decreased flatus. An abdominal CT scan showed an intestinal effusion with local intestinal obstruction. Medical treatment was ineffective; hence, he underwent a diagnostic laparoscopy. The pathologic evaluation suggested an intestinal metastatic adenocarcinoma from the primary lung cancer. Based on an real-time PCR assay, the tumor had a ROS1  fusion and responded well to crizotinib. The progression-free survival was 7 months. Physicians must be aware of the possibility of intestinal metastases from primary lung cancer. With an accurate diagnosis and thorough evaluation, patients may benefit from targeted therapy.
Keywords: lung adenocarcinoma, ROS1 , crizotinib, metastasis, small intestine