Occurrence and prognostic implications of micrometastases in lymph nodes from patients with submucosal gastric carcinoma

Background: The aims of this study were to assess the incidence of micrometastases of lymph nodes in patients with early gastric cancer invading the submucosal layer and to investigate the correlation between nodal micrometastases and malignancy potential to determine whether micrometastases of lymph nodes have prognostic significance, by use of an anticytokeratin immunohistochemical technique. Methods: A total of 2272 lymph nodes taken from 88 patients (25.8 per case) were assessed by immunohistochemical technique by use of monoclonal anti-human cytokeratin 8 antibodies. Clinicopathologic parameters and prognosis were compared between patients with and without micrometastases. Results: The incidence of nodal involvement by tumor cells in 88 patients with submucosal gastric cancer increased from 19.3% (17 patients) by hematoxylin-eosin (H&E) staining to 31.8% (28 patients) by cytokeratin immunostaining. The rate of positive node in this study increased from 1.0% (23 of 2272 nodes) by H&E staining to 2.5% (57 of 2272 nodes) by immunostaining (P = .0002). No correlation was observed between the incidence of lymph node micrometastases and various clinicopathologic parameters, including tumor site and size, histological differentiation, Lauren classification, gross tumor type, vascular and lymphatic invasion, and perineural invasion. There was no difference in disease-free survival, estimated by the Kaplan-Meier life-table method, between the micrometastasis-negative and -positive groups (95% and 92.9%, respectively). Multivariate analyses showed that tumor size and diffuse subtype by the Lauren classification were significant factors for survival time (P = .0042 and.014, respectively). Conclusions: Immmohistochemical staining with an anticytokeratin antibody seems to be of little prognostic value in patients with submucosal gastric carcinoma. Thus, this immunostaining technique does not offer a significant benefit of different strategies for additional therapy or follow-up over conventional pathologic staging with HE staining.