A patient with nonfunctional pancreatic neuroendocrine tumor and incidental metachronous colon carcinoma detected by positron emission tomography: case report

Pancreatic neuroendocrine tumors constitute about 2% of all gastrointestinal neoplasms. Approximately half of the pancreatic euroendocrine tumors are nonfunctional. Due to lack of specific symptoms, most patients with nonfunctional pancreatic neuroendocrine tumors present with locally advanced or metastatic disease. Second primary malignancies are seen very rarely in these patients. Colon carcinoma ranks third in frequency among primary sites of cancer in both men and women in western countries. Presence of a metachronous colon adenocarcinoma in a patient with nonfunctional pancreatic neuroendocrine tumor has not been reported before. We present a patient who had an asymptomatic mass in the head of the pancreas, detected by ultrasonography in 1996. The patient did not consent to operation. In 2002, after the diagnosis of an unresectable, nonfunctional pancreatic neuroendocrine tumor, interferon alpha- 2b and octreotide were started. A year after biological treatment, he refused further treatment. In 2004, during the evaluation of dissemination of the asymptomatic disease, positron emission tomography revealed a high uptake by the descending colon despite the failure of other imaging methods. After surgery for operable colon carcinoma, the patient received chemotherapy and biological therapy for both tumors. Since 2005, he has been doing well without any further treatment thus far. In conclusion, computerized tomography/magnetic resonance imaging and octreotide scintigraphy may be insufficient to show disseminated disease and asymptomatic second primary malignancies. Therefore, positron emission tomography is a valuable promising option for the evaluation of gastroenteropancreatic neuroendocrine tumors and concomitant or metachronous malignancies. Lifelong follow-up by a multidisciplinary oncology team is needed so that a long-term survival can be achieved with integrated multimodal systemic treatment approaches.