Forty cases of adenocarcinoma of the large intestine were studied immunohistochemically for chromogranin-A and a₁-antichymotrypsin on histological sections, 5 μm thick from paraffin embedded tissues. Chromogranin was present in 40% and a₁ ACT in 75% of the tumors. There weren’t any relationships between the expression of chromogranin and a₁-ACT and the age of the patient (CRM p=0.056 and a₁ ACT p=0.70), the size of the tumor (CRM p=0.07 and a₁ ACT p=0.1), the location of the tumor (CRM p=0.09 and a₁ ACT p=0.09), the lymphocytic response (CRM p=0.6 and a₁ ACT p=0.27), the sex (CRM p=0.3 and a₁ ACT p=0.45), the depth of invasion (CRM p=0.2 and a₁ ACT p=0.6), grading of the neoplasm and the status of the lymph nodes (CRM p=0.9 and a₁ ACT p=0.6). a₁-antichymotrypsin index was also independent of the tumor necrosis (p=0.5) and the survival of the patient too (p=0.07). Statistically significant differences were found at the expression of chromogranin and the tumor necrosis (p=0.008) and the survival of the patient (p<0.009). Conclusion: We consider neuroendocrine differentiation as an independent prognostic factor and chromogranin immunoreactivity as a useful method or way for detecting a subgroup with a worse prognosis among patients with colorectal cancer.

Key words: Colorectal cancer, chromogranin A, a₁-antichymotrypsin.

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