Successful treatment with afatinib for pancreatic metastasis of lung adenocarcinoma: a case report.

Metastatic lung cancer of the pancreas is rare and optimal treatment protocols have not been determined. An asymptomatic 53-year-old man with primary lung cancer underwent a right lower lobectomy and was diagnosed with acinar adenocarcinoma, pT2bN2M0 stage IIIA. An epidermal growth factor receptor (EGFR) mutation (exon 19 deletion L747-A750insP) was detected in the primary tumor. Adjuvant platinum-based chemotherapy was administered. The patient's serum carcinoembryonic antigen (CEA) level had increased to 38.6 ng/mL 32 months after surgery, and positron emission tomography-computed tomography (PET-CT) revealed a 2.5-cm, hypermetabolic nodule in the pancreatic body. Using endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA), the nodule was pathologically diagnosed as a pancreatic metastasis of lung adenocarcinoma. The EGFR status of the pancreatic metastasis was confirmed to be the same as that of the primary lung tumor. The patient started afatinib therapy and his serum CEA level immediately decreased and remained at approximately the reference limit. On a follow-up PET-CT scan after 10 months of treatment with afatinib, the metastatic nodule in the pancreas had disappeared and no accumulation of fluorine-18-deoxyglucose (FDG) was detected. To the best of our knowledge, this is the first reported case of a complete response of pancreatic metastatic lung adenocarcinoma to EGFR-tyrosine kinase inhibitors (TKIs).