Evaluation of the 5th edition of the TNM classification for gastric cancer: improved prognostic value

Abstract

SummaryThe main change in the 5th edition (1997) of the TNM classification for gastric cancer compared to the 4th edition (1987) is the use of the number of involved nodes instead of the location of positive nodes. As a result stage grouping is also altered. A second change is the requirement for the examination of at least 15 nodes to justify the N0 status. Patients with fewer examined negative nodes are unclassifiable (Nx). Data were retrieved from a randomized trial database comparing D1 and D2 dissection and 633 curatively operated patients were included. According to the criteria of the 5th edition, 39% of the node-positive patients had another N stage compared to the 4th: 21% had a lower and 18% had a higher stage. 5-year survival rates according to the 4th edition N0, N1 and N2 groups were respectively 72%, 34% and 27%. According to the 5th edition these percentages were for the N0, N1, N2, N3 and Nx groups respectively 75%, 38%, 19%, 8% and 65%. The former 1987 N1 and N2 group were significantly split into three new N 1997 groups (P = 0.006, respectively P < 0.0005). The Cox's regression analysis showed the N 1997 classification to be the most important prognostic variable, with a higher prognostic value than N 1987. In addition, the new TNM stage was also a better prognosticator. The requirement for examining at least 15 nodes, however, could not be fulfilled in 38% of all nodenegative patients and we found that a minimum of 5 consecutive negative lymph nodes is a reliable number for staging purposes. We conclude that the 5th edition of the TNM classification provides a better estimation of prognosis, however, examination of at least 15 negative regional lymph nodes is too high a threshold and 5 gives similar prognostic value. 64-71 © 2001 Cancer Research Campaign doi: 10.1054/ bjoc.2000.1548, available online at http://www.idealibrary.com on http://www.bjcancer.com abdominal washing, 35 due to resection-line involvement and 3 patients due to positive cytology as well as positive margins. In 5 of the remaining 639 R0 patients, no primary tumour could be found and in one patient the T-stage could not be determined due to inadequate specimen handling. The present report will therefore be based on 633 patients, including 44 patients who died in the post-operative phase (in-hospital death or within 30 days after surgery), since the postoperative mortality was different between the D1 and D2 group (15 versus 29 patients). Survival time was calculated from the date of surgery until death or last follow-up alive. The range in follow-up time of patients still alive was 6.0 to 10.2 years, with a median follow-up of 7.9 years. ClassificationsIn (Table 2). As said before, we had to make additional to the official 1997 TNM definitions, a Nx category and consequently an 'unclassifiable' TNM category for the node-negative patients with <15 lymph nodes examined (TNMx). StatisticsThe χ 2 test was applied to assess differences in the distribution of patients among groups. The Mann-Whitney test was used for comparis...

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