[Clinicopathologic characteristics of colorectal neuroendocrine tumor]

Colorectal neuroendocrine carcinoma is a rare neoplasm exhibiting fulminant progression and having poor prognosis. The purpose of this study is to verify the clinicopathologic characteristics of colorectal neuroendocrine carcinoma.

From June 1997 to December 2004 at Asan Medical Center, ten patients were originally identified as colorectal neuroendocrine carcinoma on the basis of H&E and immunohistochemical staining (IHC). Carcinoid tumors were excluded in this study. Medical records of thirteen patients were reviewed retrospectively.

Ten patients (0.2%) with colorectal neuroendocrine tumors were identified from 4,512 patients with colorectal cancer; ten neuroendocrine carcinomas and three adenocarcinomas with neuroendocrine differentiation. Their median age was 60 (41-83) years. The subjects consisted of six males and seven females. Nine tumors were located in the rectum, two in the sigmoid, and each one in the transverse colon and cecum, respectively. Nine of ten neuroendocrine carcinomas expressed synaptophysin, but chromogranin A were expressed in four. All patients were advanced at the time of diagnosis, with AJCC TNM staging: stage IIIB (n=2), stage IIIC (n=3), and stage IV (n=8). The median survival for ten neuroendocrine carcinomas and three adenocarcinomas with neuroendocrine differentiation were 16.4 months and 30 months, respectively. Five patients who received chemotherapy showed median survival of 32 months (stage III) and 17.5 months (stage IV), whereas other five patients without chemotherapy died with a median survival of 6.2 months.

Colorectal neuroendocrine tumors are extremely rare showing aggressive behavior biologically, i.e fulminant early distant metastasis. Nevertheless, improved survival may be achieved by aggressive multimodality therapy.