The differences in the stage classification for node-positive colorectal cancer between the United States and Japan: A single institution experience.

Abstract

e14139 Background: In the United States, the stage classification by the number of lymph node metastasis (LNM) is adopted in TNM classification 7th edition. In Japan, the stage classification by the distribution of LNM was modified to that by the number of LNM in order to integrate with TNM classification in Japanese classification of colorectal carcinoma second English edition. We retrospectively examined the possibility of predicting prognosis by the number of LNM and considered the differences between TNM classification and Japanese classification. Methods: Two hundred and seventy-five patients with LNM who underwent curative surgery for colorectal cancer at our department between January 1992 and December 2004 were enrolled in this study. All patients were followed for 5 years after the operation. At first, we calculated cancer-specific survivals according to the number of LNM in order to examine whether the stratifications of prognosis by the number of LNM is appropriate or not. Secondary, clinicopathological factors and survival data were analyzed to determine prognostic factors. Finally, we considered the differences between TNM classification and Japanese classification. Results: When comparing cancer-specific survivals between the patients with the number of LNM of 1 and 2-3 and 4 or more, cancer-specific survivals were well stratified (both; p=0.006). According to the multivariate analysis using clinicopathological factors, invasion depth (T4) (p=0.007, odds ratio=2.230), venous invasion (moderate-severe) (p=0.003, odds ratio=2.577) and the number of LNM (p=0.0002, odds ratio=1.201) were significantly independent prognostic factors. In Japanese classification, there was a significant difference in cancer-specific survivals between Stage IIIa and IIIb (p<0.0001). On the other hand, in TNM classification, cancer-specific survivals in Stage IIIA, IIIB and IIIC were stratified into three groups with significant differences (IIIA vs IIIB; P=0.01, IIIB vs IIIC; p<0.0001). Conclusions: In comparison of Japanese classification and TNM classification, TNM classification seems to be superior to Japanese classification.