Lymph node metastasis in cancer of the middle-third stomach: Criteria for treatment with a pylorus-preserving gastrectomy

A retrospective study was conducted to establish the criteria for performing a pylorus-preserving gastrectomy. This study was performed on 491 patients who had cancer of the middle-third stomach and had been curatively treated with a distal gastrectomy. The incidence of node metastasis for each lymph node station (the group of regional lymph nodes which have been anatomically defined and classified by the Japanese Classification of Gastric Carcinoma) was evaluated with reference to the depth of invasion, tumor size, and circumferential location, to show any significant correlations with an increase in tumor diameter or in the depth of tumor invasion. The benefits of resecting each station was then evaluated based on the incidence of metastasis to each station and the rate of long-term survivors among those with metastasis to each station. The benefit was substantial for the lymph nodes along the lesser curvature, along the right gastroepiploic artery, and at the base of the left gastric artery, while the advantages were almost negligible for the suprapyloric nodes and right paracardial nodes. In conclusion, carcinoma that fulfills either of the following conditions may thus be indicated to undergo a pylorus-preserving gastrectomy: (i) restricted to a depth of m of sm1, (ii) a depth of sm2 or mp with a diameter of less than 2 cm, (ii) a depth of sm2 or mp and located in the greater curvature.