Objective: To ascertain the risk of locoregional lymph node metastases from colorectal cancer, we compared microscopic pathological characteristics of the primary tumor with the expression of the nm23-H1 protein.
Methods: The nm23-H1 expression of 100 colorectal carcinomas and corresponding non-neoplastic mucosa was analyzed immunohistochemically at the time of primary curative surgery (R0 resection). Conventional histopathological factors (depth of infiltration, grade of differentiation, invasion of lymph vessels or veins) that are proven indicators for metastatic involvement of locoregional lymph nodes were examined in all cases.
Results: Of 45 tumors with lymph node metastases, 42 (93%) had a low nm23-H1 expression whereas only 35 (78%) were of high-risk histology (G3, G4, or lymphatic invasion). Therefore, nm23-H1 expression within the primary tumor indicated the lymph node status with a sensitivity of 93% and a negative predictive value of 92%. The classic pathohistological factors (high risk vs low risk) had a sensitivity of 78% and a negative predictive value of 77%, respectively.
Conclusion: Reduced expression of nm23-H1 within primary colorectal carcinomas could serve as an additional independent marker in estimating the nodal metastatic potential of these tumors.