Immunohistochemical study on endocrine-like tumor cells in colorectal carcinomas

Abstract

AIM: To evaluate the clinical significance of endocrine-like tumor cells in human colorectal carcinomas.

METHODS: The immunohistochemistry method (ABC) using a rabbit polyclonal antibody against human chromogranin A (CGA) was employed to determine changes in endocrine-like tumor cells from the surgically resected colorectal carcinoma tissues of patients (35 males and 27 females, aged from 19 to 78 years, with a mean age of 50.3 years). Of the 62 specimens, 44 were from rectal carcinomas, 18 from colonic carcinomas, 14 from lymph nodes and 48 from non-involvement. Dukes classification revealed 19 of the cases were in stage A, 29 cases were in stage B and 14 cases were in stage C. All of the specimens were fixed with 10% formalin, embedded with paraffin and cut into 5 μm sections. Additionally, the correlations among CGA-positive tumor cells, as well as the clinicopathologic data, age and sex of the patients, were also investigated.

RESULTS: CGA-positive tumor cells were found in 35.5% of the patients with colorectal cancers, representing 20.0% (5 of 25) and 45.9% (17 of 37) of the aged and non-aged, respectively. These differences were significant (χ² test, P < 0.05). Nevertheless, no significant correlations were found between the CGA-positive tumor cells and the sex, Dukes stages, tumor location, degree of histological differentiation or presence of lymph node metastasis.

CONCLUSION: The low incidence of endocrine-like tumor cells found in the aged patients may be a new pathological feature for colorectal carcinomas, which could explain why the aged patients usually had a better prognosis. The exact significance of these findings requires further characterization.

Key Words: Colorectal neoplasms/pathology; Chromogranin A; Immunohistochemistry