Immunohistochemically Demonstrated Lymph Node Micrometastasis and Prognosis in Patients With Otherwise Node-Negative Hilar Cholangiocarcinoma

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Abstract
Objective To investigate whether immunohistochemically demonstrated lymph node micrometastasis has prognostic significance in patients with histologically node-negative (pN0) hilar cholangiocarcinoma. Summary Background Data The clinical significance of immunohistochemically detected lymph node micrometastasis recently has been evaluated in various tumors. However, no reports have addressed this issue with regard to hilar cholangiocarcinoma. Methods A total of 954 lymph nodes from surgical specimens of 45 patients with histologically node-negative hilar cholangiocarcinoma who underwent macroscopically curative resection were immunostained with monoclonal antibody against cytokeratins 8 and 18. The results were examined for relationships with clinical and pathologic features and with patient survival. Results Lymph node micrometastases were detected immunohistochemically in 11 (24.4%) of the 45 patients, being found in 13 (1.4%) of 954 lymph nodes examined. Of the 13 nodal micrometastases, 11 (84.6%) were found in the N2 regional lymph node group rather than N1. Clinicopathologic features showed no associations with lymph node micrometastases. Survival curves were essentially similar between patients with and without micrometastasis. In addition, the grade of micrometastasis showed no effect on survival. The Cox proportional hazard model identified microscopic venous invasion, microscopic resection margin status, and histologic differentiation as significant prognostic factors in patients with pN0 disease. Conclusions Lymph node micrometastasis has no survival impact in patients with otherwise node-negative hilar cholangiocarcinoma. The authors do not recommend extensive lymph node sectioning with keratin immunostaining for prognostic evaluation.