Neuroendocrine differentiation in colorectal carcinomas: assessing its prognostic significance

There is evidence that colorectal carcinomas with extensive neuroendocrine features have a substantially worse prognosis than those without, but the frequency and clinical significance of neuroendocrine features in conventional carcinomas has not been settled since few studies have been performed, with conflicting results. The aim of the study was to investigate neuroendocrine differentiation in colorectal carcinomas in relation to its prognostic significance.

In 50 patients with colorectal carcinoma, the extent and intensity of staining with each of the three antibodies (chromogranin A, neuron-specific enolase and synaptophysin) were determined and correlated with the histologic type, grade, stage of the tumor and survival time ot the patients.

We observed chromogranin A expression in 38%, neuron-specific enolase expression in 26%, and synaptophysin expression in 6% of the tumors. Chromogranin A was the most frequently and strongly expressed marker in our study. Of the three antibodies studied, only chromogranin A positivity was correlated with grade and stage of the tumors and was associated with a decreased effect on survival.

Our results show that chromogranin A is the most sensitive and specific neuroendocrine marker. Chromogranin A positivity appears to bear a poor prognosis in patients with colorectal cancers.