Effectiveness of afatinib in lung cancer with paralytic ileus due to peritoneal carcinomatosis

A 61‐year‐old never‐smoking woman with stage IV lung adenocarcinoma with initially unknown epidermal growth factor receptor (EGFR) status, lung metastasis, pleural dissemination, and malignant pleural effusion in 2007 received 10 prior anti‐cancer regimens including gefitinib as second‐ and ninth‐line treatments, with minimal efficacy with gefitinib. EGFR mutation analysis performed in pleural effusion specimens during ninth‐line gefitinib was negative. In 2015, she developed progressive disease with peritoneal dissemination. Few/absent bowel sounds and no gross features of mechanical obstruction on the imaging led to the diagnosis of paralytic ileus. Blood test revealed elevated C‐reactive protein (CRP). EGFR mutation analysis revealed S768I point mutation in EGFR exon 20 without the T790M resistance mutation in pleural and peritoneal effusion cytology specimens. She received afatinib (20 mg once daily) as 11th‐line treatment, with resolution of peritoneal carcinomatosis and CRP normalization, confirmed by follow‐up computed tomography. At 12 months after afatinib initiation, there was no symptomatic recurrence or disease exacerbation.