Micrometastasis in regional lymph nodes of extirpated colorectal carcinoma: immunohistochemical study using anti-cytokeratin antibodies AE1/AE3.

OBJECTIVE

The main objectives of this study were to identify, by immunohistochemistry, possible micrometastasis in the regional lymph nodes previously considered free by conventional histopathological examination, and to assess their influence on the survival of patients with colorectal cancer that had been extirpated in a radical manner.

PATIENTS AND METHODS

From 38 patients with Dukes B staging (Colorectal Carcinoma Stage II (T3 N0 M0 or T4 N0 M0)) colorectal carcinoma, 383 lymph nodes were studied in paraffin blocks that had previously been considered free by conventional histopathological examination. These were submitted to immunohistochemical study using AE1/AE3 anti-cytokeratin monoclonal antibodies to identify neoplastic epithelial cells.

RESULTS

Seven lymph nodes (1.82%) in six patients (15.78%) contained micrometastasis. The survival of the patients with extirpated colorectal carcinoma staged as Dukes B who had lymph node metastasis was less than in the group of patients without micrometastasis, although these values were not statistically significant.

CONCLUSION

This immunohistochemical method can be employed successfully in the detection of neoplastic cells in lymph nodes previously considered free. In this study, there was a trend towards lower survival in node-positive patients but this did not reach statistical significance.