Immunohistochemical detection of lymph node microinvolvement in node-negative gastric cancer

Background. Despite curative resection of the primary tumor with extensive dissection of lymph nodes, some patients with node-negative gastric cancer die of local relapse or metastatic disease. Microinvolvement of regional lymph nodes may play an important role in the prognosis. Methods. To evaluate the incidence and prognostic implications of regional lymph node microinvolvement in node-negative gastric cancer, we retrospectively analyzed tissue samples from 51 patients operated on for primary gastric cancer. They had tumors that invaded beyond the muscularis propria, but without metastasis to the lymph nodes, shown by the conventional H&E staining method. The regional lymph nodes were examined immunohistochemically, using monoclonal antibodies against cytokeratin. Results. Microinvolvement was found in 4.8% of lymph nodes (67/1390) and in 43.2% of the patients (22/51). The clinical outcome of the patients with microinvolvement was not significantly different from those without it. However, no patient died in the no-microinvolvement group, while three patients in the microinvolvement group died of recurrence. Conclusion. The incidence of microinvolvement in conventionally negative lymph nodes cannot be ignored, and detecting microinvolvement may be important for predicting recurrence of gastric cancer. Received for publication on April 26, 1999; accepted on Sept. 14, 1999