S3730 Metastatic High-Grade Neuroendocrine Tumor of the Colon: A Rare Disease With Poor Outcome

Introduction: Neuroendocrine carcinoma of colorectum (NET) is rare. It arises from gut, pancreas and lung cells. Clery et al. first reported high grade neuroendocrine carcinoma (HGNEC) of colorectum. Incidence is 2 per million person-years. Classification is based on mitotic rate and/or Ki-67 labeling index. 20 mitoses/10 high power fields or Ki- 67 index of more than 20% indicates poorly differentiated NET. Treatment includes surgery and chemoradiation for localized disease and chemotherapy for metastatic disease. Median survival is 14.7. We present a case of HGNEC of the colon metastatic to the liver. Case Description/Methods: A 53-year-old African American man presented with abdominal pain, diarrhea and weight loss. Personal and family history was unremarkable. He never had a screening colonoscopy. Physical examination was unremarkable. Labs showed anemia, leukocytosis, and elevated alkaline phosphatase. A computed tomography (CT) scan showed liver metastasis. Colonoscopy showed an obstructing mass in the splenic flexure. Biopsy showed HGNEC. Tumor stained for cam 5.2, synaptophysin and chromogranin. Ki-I 67 was 90%. Left hemicolectomy and biopsy of hepatic metastasis was performed. He received platinum-based chemotherapy. Patient developed hyperbilirubinemia with significant metastatic disease on repeat CT. Patient pursued comfort care, and he passed away. Discussion: HGNEC constitutes 0.6% of all malignant colorectal cancers. The median age at diagnosis is 65 years, predominantly in Whites. Our patient was African American and presented at a younger age. Histologically, they are similar to small cell lung cancer (SCLC). Unlike SCLC, smoking is not a risk factor. They are non-hormone producing and present with metastatic disease. They may be associated with an adenoma and familial adenomatous polyposis. Early-stage tumors are treated with surgery and chemotherapy. Advanced stages treated with combined chemotherapy and surgical resection shows better outcome. Our patient did poorly with this therapeutic approach. The chemotherapeutic regimen is platinum-based Lower Ki-67 (<55%) are associated with poor response to chemotherapy. Liver metastases are treated with surgery, trans arterial treatments. Our patient responded poorly despite having high Ki-67 levels (>90%). Patient and tumor factors may be important in response to chemotherapy. A screening colonoscopy might have changed the patient's outcome. A dedicated database regarding this disease may improve patient's outcome.