The Number of Metastatic Lymph Nodes: A Promising Prognostic Determinant for Gastric Carcinoma in the Latest Edition of the TNM Classification Yasuhiro Kodera, MD, Yoshitaka Yamamura, MD, Yasuhiro Shimizu, MD, Akihito Torii, MD, Takashi Hirai, MD, Kenzo Yasui, MD, Takeshi Morimoto, MD, Tomoyuki Kato, MD, and Tsuyoshi Kito, MD Background: The number of metastatic regional lymph nodes determines the new pN categories in the 5th edi- tion of the TNM classification. Study Design: Our retrospective study was conducted to compare the new method of defining lymph node status with the conventional classification, consisting of the anatomic extent of lymph node metastases, a well- established prognostic factor. The study was based on clinical data for 493 patients with gastric carcinomas who underwent potentially curative operations and had histologically confirmed nodal metastases. These pa- tients were stratified into 1) n categories according to the Japanese Classification of Gastric Carcinoma, 2) the new pN categories, and 3) the pN categories determined by the number of metastatic perigastric nodes resected by standard D1 gastrectomy. Survival data were analyzed for each group. Results: The number of metastatic nodes after D2 lymphadenectomy reflected prognosis well and was shown by multivariate analysis to be a strong indepen- dent prognostic factor. When the classification was per- formed limited to the metastatic perigastric nodes, stage migration was evident, but the variable remained com- petent as a prognostic indicator. Conclusions: The number of metastatic nodes is a promising determinant in the new international stage classification. (J Am Coll Surg 1998;187:597–603. © 1998 by the American College of Surgeons) The absence or presence and the anatomic extent of histologically confirmed lymph node metastasis are important prognostic factors for gastric carcinoma. 1,2 These factors, expressed in terms of the pN categories proposed by the TNM classification 3 or the n cate- gories of the Japanese Classification for Gastric Car- cinoma (JCGC), 4 have been essential components of the widely used stage classification for gastric carci- noma. In the most recent edition of the TNM clas- sification, 5 however, the anatomic extent of lymph node metastasis was replaced by the numbers of met- astatic lymph nodes, another known prognostic fac- tor, 6,7 to define new pN categories. In this retrospective study, we compared these 2 modes of lymph node status assessment. The com- parison was based on the clinicopathologic data of 493 consecutive patients with gastric carcinoma and nodal metastases treated in a single institution, Aichi Cancer Center. At this institution, a typical Japanese- style operation with extended lymphadenectomy (D2 resection) is the standard surgical procedure. Stratification was performed also with numbers lim- ited to the metastatic perigastric nodes. The D1 op- eration, a standard procedure in the West, generally removes only the perigastric lymph nodes, and this is the basis for the histopathologic information from which the pN categories often have to be determined. METHODS During a 10-year period between 1983 and 1992, 1,913 patients with gastric carcinomas underwent surgery at Aichi Cancer Center. Among these, 493 patients with nodal metastasis, without invasion to the adjacent structures, and without distant metasta- sis (except for metastasis to n3 or n4 nodes, as de- scribed later) were treated with potentially curative D2 or D3 resection. Carcinomas with invasion to the adjacent viscera (pT4) were excluded because these are classified as stage IV in the 5th edition of the TNM classification regardless of the pN status. The Received April 13, 1998; Revised August 4, 1998; Accepted August 6, 1998. From the Department of Gastroenterological Surgery, Aichi Cancer Center, Nagoya, Japan. Correspondence address: Yasuhiro Kodera, MD, Department of Gastroenter- ological Surgery, Aichi Cancer Center, 1-1, Kanokoden, Chikusa-ku, Nagoya, Aichi 464, Japan. 597 © 1998 by the American College of Surgeons ISSN 1072-7515/98/$19.00 Published by Elsevier Science Inc. PII S1072-7515(98)00229-4