New method to evaluate the therapeutic value of lymph node dissection for gastric cancer.

The results of 1281 potentially curative resections for advanced gastric cancer performed at the National Cancer Center Hospital between 1972 and 1986 were studied using a novel approach which circumvents the stage migration phenomenon. The incidence of metastasis and the 5-year survival rate of patients with positive nodes were calculated independently for each lymph node 'station', without any reference to overall pathological nodal stage. The therapeutic value of extended lymph node dissection was estimated by multiplication of incidence of metastasis and percentage 5-year survival rate of patients with metastasis for each station. The incidence of metastasis ranged from 2.4 per cent to 66 per cent and the 5-year survival rate of affected patients from 0 to 58.7 per cent in perigastric stations, depending on the site of the primary tumour. The incidence of metastasis was between 3.0 per cent and 44.4 per cent in the second tier of nodes (n2), and the 5-year survival rate ranged from 0 per cent to 47.5 per cent. The majority of second-tier stations showed evidence of benefit from node dissection.