[Preoperative diagnosis and surgical treatment for lymph node metastasis in gastric cancer]

In order to clarify the preoperative diagnostic ability for lymph node metastasis, images from magnetic resonance imaging (MRI), computed axial tomography (CT) and ultrasonography (US) were evaluated in 200 gastric cancer patients. The long-term results of 2,000 gastric cancer patients who had undergone gastrectomy were also studied to evaluate the effectiveness of lymphadenectomy. 1) Preoperative diagnosis of lymph node metastasis: The detection rate of lymph nodes around the stomach was 34.1% in MRI, 18.7% in CT and 5.0% in US. The incidence of metastasis was over 80% when the size of lymph node imaged was 1.5 cm and over, against 25% for lymph nodes less than 1.0 cm in size. The detection rate of metastatic lymph node according to the mode of metastasis was 88% for macro-nodular type, 66% for micro-nodular type, 57% for diffuse type in MRI, 70, 41 and 15% in CT, and 38, 3, 0% in US, respectively. Therefore, MRI was most useful for detecting metastatic lymph node preoperatively. 2) Long-term results of gastric cancer with lymph node metastasis: The cumulative 5-year survival rate was 84.2% in n0, 56.1% in n1, 33.7% in n2, 16.5% in n3, and 5.1% in n4 patients. Satisfactory long-term results were obtained for n2 or less patients without serosal invasion. Moreover, by paraaortic lymph node dissection, the cumulative 5-year survival rate in n4 patients was 16.4% (27.8% for cases with radical resection). These results showed the effectiveness of lymph node dissection for gastric cancer.