Purpose: This report outlines the incidence and the clinical features of patients with a neuroendocrine (NE) neoplasm of the colon and rectum and describes, in detail, their histologic and immunohistochemical findings. Also, we attempted to
determine
the impact of several clinical variables, including tumor stage, tumor location, NE pattern, and cellular subtype on survival. Method: Of 690 colorectal cancers operated on from April 1990 to November 1998 at Chungnam National University
Hospital,
41
cases were originally diagnosed as poorly differentiated adenocarcinoms on the basis of conventional light microscopy. Paraffin blocks from the aforementioned cases were retrieved, and sections were immunostained with antibodies to human
chromogranin A,
neuron specific enolase, and synaptophysin. Results: Of the 690 cases of colorectal caner, 35 cases (5.1%) of NE neoplasm were identified retrospectively: 28 males and 7 females. About 90% of the tumors were located at the cecum and the
rectosigmoid.
Pathologic stages were as follows: modified Dukes stage B2, 6; stage C1, 8; stage D1, 12; and stage D2, 9. The most common metastatic site at the time of diagnosis was the liver (8/9). Four NE patterns were identified: pure NE (n=4), and
predominantly
NE (n=8), equal NE and exocrine (n=4), and predominantly exocrine (n=19). Two cellular subtypes were identified: well-differentiated (n=3) and intermediate (n=32) cells. Survival statistically correlated with stage (p=0.03), but not with age,
sex,
tumor
location, NE pattern, or cellular subtype. Conclusion: This study suggests that NE neoplasms of the colon and rectum are more frequent than previously believed. Since a NE neoplasm is believed to be an extremely biologically aggressive tumor,
recognition of a NE neoplasm is very important because of its evident clinical and therapeutic implications.
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