Detection of lymph nodes micrometastases in Dukes' A and B colorectal cancer using anti-cytokeratin antibodies AE1/AE3

Abstract

Aim: To detect lymph nodes micrometastases and analyze its correlation with clinicopathological parameters in Dukes' A and B colorectal cancer patients.

Methods: One hundred and fourteen patients with colorectal cancer (Dukes' A 16; Dukes' B 98) undergoing curative operation without histological lymph nodes metastases were studied between 2001 and 2003. A total of 2,481 lymph nodes were analyzed using monoclonal cytokeratin antibody AE1/AE3 (DAKO, Carpinteria, CA) for immunohistochemistry.

Results: In total, 33 (29%) patients were positive for cancer cell by immunohistochemistry. In 31 (94%) patients of them positive nodes showed single tumor cell or small groups of tumor cells; and tumor deposits measuring 0.2 and 0.37 mm in diameter in another 2 (6%) patients. Micrometastases were mainly located in the subcapsular sinus or paracortical sinus. There was no correlation between the positive lymph nodes and gender, age, tumor site, tumor size, histological type, histological grade, invasion depth, Dukes' staging and microsatellite instability (P>0.05).

Conclusion: Our findings suggest that immunohistochemical technique using monoclonal cytokeratin antibody AE1/AE3 may be a sensitive and reliable method for detecting lymph nodes micrometastases in Dukes' A and B colorectal cancer. The clinical significance of lymph nodes micrometastases is still not confirmed.

Figure 1

Representative photographs of micrometastases detected by immunohistochemistry using monoclonal cytokeratin antibody AE1/AE3. A: arrowhead indicates a cancer cell located in the paracortical sinus showing morphological characteristics of malignant cells including a large nucleus and condensed nuclear small body; B: arrowhead points to three cancer cells located in subcapsular sinus. Original magnification: A, ×200; B, ×200.

Figure 2

Representative photographs of micrometastases detected by immunohistochemistry using monoclonal cytokeratin antibody AE1/AE3. A: arrowhead indicates a single cell in the positive node; B: arrowhead shows small groups of cells in the positive node; C: arrowhead points to large tumor deposits in the positive node. Original magnification: A, ×400; B, ×400; C, ×200.