The effectiveness of the new (7th) UICC N classification in the prognosis evaluation of gastric cancer patients: a comparative study between the 5th/6th and 7th UICC N classification.

BACKGROUND

The most important prognostic factor after curative surgery for gastric carcinoma is the presence of lymph node metastases. According to the 7th edition of the UICC TNM staging system for gastric cancer, N classification was categorized as N0 (no regional lymph node metastasis), N1 (1-2 regional lymph node metastases), N2 (3-6 regional lymph node metastases), and N3 (7 or more regional lymph node metastases). The purpose of this study was to evaluate the rationality of the new UICC/AJCC N classification in comparison with the 6th UICC classification.

METHODS

From August 2002 to July 2006, 295 patients with gastric cancer underwent curative resection with D2 lymph node dissection by a single surgeon. We analyzed retrospectively the significant prognostic factors and identified the suitability of the 7th UICC N staging system.

RESULTS

According to the 7th UICC N classification, the 5-year cumulative survival rates (5-YSR) of N0, N1, N2, N3a, and N3b were 89.7, 73.6, 54.9, 23.1, and 5.4%, respectively (P < 0.0001). Using univariate analysis, the N classification of the 7th and 6th UICC/AJCC TNM staging system, T classification of the 7th UICC TNM staging system, size and location of tumor, and histology were associated with the overall survival of gastric cancer after curative surgery. However, Cox regression multivariate analysis showed the 7th UICC N classification was an independent prognostic factor instead of the 6th UICC N classification (P < 0.0001).

CONCLUSION

The 7th UICC classification for lymph node metastasis is thought to be a more reliable prognostic factor for gastric cancer than the 6th classification.