Prevalence and Prognostic Significance of Neuroendocrine Differentiation in Colorectal Carcinomas.

The prognostic significance of neuroendocrine differentiation in colorectal carcinoma is uncertain. We analyzed 289 moderately differentiated (grades II and Ill) colorectal carcinomas for neuroendocrine differentiation by immunohistochemistry and in situ hybridization. The tumors were divided into three groups based on the presence of and the numbers of neuroendocrine cells, with group I having no neuroendocrine cells, group II having <1 positive cell/mm(2), and group Ill with >1 positive cell/mm(2). In situ hybridization with probes for chromogranin A and B detected almost twice as many neuroendocrine cells as did immunostaining with an antibody for chromogranin A. There was no prognostic difference associated with the presence or absence of neuroendocrine differentiation in this group of moderately differentiated carcinomas. These results indicate that the presence of neuroendocrine cells detected by expression of chromogranin protein or mRNA does not influence prognosis in moderately differentiated colorectal carcinomas.