A case report of successfully treated metachronous gastrointestinal stromal tumor and colon cancer

Abstract

The diagnosis of gastrointestinal stromal tumor (GIST) has become relatively common in recent years, but little is known about its association with other malignancies. We present a rare case of successfully treated metachronous GIST and colon cancer with concurrent FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) chemotherapy and imatinib. A 63-year-old man presented with abdominal pain that had started 2 weeks ago, and endoscopic ultrasonography showed masses that were compatible with GIST on the duodenum. He underwent Whipple surgery. One year after the GIST diagnosis, two liver masses were found on abdominal computed tomography images taken for surveillance. A liver biopsy showed metastatic adenocarcinoma, not GIST. Colonoscopy was then performed to identify the primary site of the metastatic adenocarcinoma in the liver, and sigmoid colon cancer was found. He received 12 cycles of adjuvant FOLFOX concurrently with adjuvant imatinib. There were no serious adverse events of grade 3 or higher from either imatinib or chemotherapy. He has completed adjuvant imatinib and FOLFOX chemotherapy and there is no evidence of disease recurrence. When a synchronous or metachronous tumor is found in a GIST patient, the clinician should keep in mind the possibility of another primary tumor of different histopathology, as well as GIST recurrence.