Colon cancer chemotherapy for a patient with CDX2-expressing metastatic thymic adenocarcinoma: a case report and literature review

We report the case of a 59-year-old man with thymic adenocarcinoma who was treated with colon cancer chemotherapy. He was referred to our hospital for an anterior mediastinal mass and multiple bone metastases that were found by computed tomography. Needle biopsy of the mediastinal tumor revealed a caudal-type homeobox 2 (CDX2)-positive adenocarcinoma. Neither upper nor lower gastrointestinal endoscopic examinations revealed any evidence of a primary tumor. The patient was administered CapeOX (capecitabine and oxaliplatin) and FOLFIRI (fluorouracil, leucovorin and irinotecan)/cetuximab. He died 6 months after diagnosis. Primary thymic adenocarcinoma was confirmed by autopsy. As far as we know, this is the first report in which colon cancer chemotherapy was used to treat CDX2-positive metastatic thymic adenocarcinoma.