New Metastatic Lymph Node Ratio System Reduces Stage Migration in Patients Undergoing D1 Lymphadenectomy for Gastric Adenocarcinoma

Abstract

Background The AJCC/UICC staging system for gastric cancer incorporates the absolute number of metastatic lymph nodes (N status) and is optimally used when ≥15 nodes are examined. The ratio of metastatic to examined nodes (N ratio) is an effective prognostic tool, but has not been examined in Western patients undergoing primarily D1 lymphadenectomy. Methods 257 patients with gastric adenocarcinoma who underwent gastric resection between 1995 and 2005 at our institution were examined. Novel N ratio intervals were determined using the best cutoff approach (Nr0: N ratio=0 and ≥15 nodes examined; Nr1: 0 ≤ N ratio ≤ 0.3, Nr2: 0.3 < N ratio ≤ 0.7, and Nr3: N ratio > 0.7). Overall survival was examined according to N status and N ratio. Results 83% of patients underwent D1 lymphadenectomy with a median of 14 lymph nodes examined. Overall survival stratified by N status was significantly different in patients with <15 nodes examined compared to those with ≥15 nodes examined. When we stratified N ratio intervals, there was no significant difference in overall survival in patients with <15 vs. ≥15 nodes examined. On multivariate analysis, N ratio but not N status was retained as an independent prognostic factor. Conclusions The use of N status for staging patients undergoing primarily D1 lymphadenectomy results in significant stage migration due to varying numbers of nodes examined. Use of N ratio reduces stage migration and may be a more reliable method of staging such patients.

Lymph node ratio is a critical prognostic predictor in gastric cancer treated with S-1 chemotherapy

“…Lymph node ratio has already been reported as a prognostic factor in various series of advanced gastric cancer [12][13][14][15][16][17][18], but the prognostic relevance was observed again in this study with the Japanese population treated by the current standard of care.…”

“…Lymphatic permeation (ly) and vascular permeation (v) are defined as ly0, ly 1, ly 2, and ly 3 and v0, v1, v2, and v3 by infiltrative grade, but we classified ly and v as absence or presence. Percentage of metastatic lymph nodes, as lymph node ratio greater than or equal to a certain value designated by the researchers, has been defined as one of the most promising prognostic predictors by our previous studies [12][13][14] and elsewhere [15][16][17][18]. Histologically, there are two major types of gastric adenocarcinoma (Lauren's classification).…”

The evaluation of metastatic lymph node ratio staging system in gastric cancer

“…To evaluate the rN staging system, some previous reports excluded patients with fewer than 16 LNs retrieved [16,20,22]; some researchers preferred the patients treated by limited lymphadenectomy, [9,10,18,23]; and some centers evaluated the rN system as an independent prognostic factor in gastric cancer regardless of the type of lymphadenectomy, or in both [15 and B15 LNs examined [17,19,24,25], as we did in our report. All the reports indicated that the rN staging system has superiority in prognosis assessment compared with the traditional AJCC pN system.…”

“…The Cox multivariate analysis showed that rN has a prognostic value independent of the extent of lymphadenectomy. Many previous reports used Cox multivariate examinations, including both pN stage and rN stage, for proving the superiority of the LN ratio system [9,[15][16][17][18][19][20]. The pN and rN systems, two definitions of classifications for staging lymph node status, were highly correlated.…”

“…However, there is much controversy regarding the most appropriate cutoff ratio because the ratios differ among investigators. The following cutoff values have been proposed: 0, 0.20, 0.50 [10,24], 0, 0.30, 0.60 [15,25], 0, 0.10, 0.25 [9,16,20], 0, 0.30, 0.70 [17], 0, 0.015, 0.40 [23], 0, 0.10, 0.25 [19], 0, 0.25, 0.50 [18], and 0, 0.10, 0.40 [22]. The cutoff values showed great variety in different countries, even in different centers in the same country.…”