Comparative Study between TNM Staging according to Number of Metastatic Lymph Node and UICC-TNM Staging in Stomach Cancer

Kim, Song Cheol; Yang, Han Kwang; Kim, Yong Il; Kim, Jin Pok

Abstract

Staging of cancer is very important for estimation of prognosis and treatment effect in cancer treatment. In gastric cancer, the TNM staging system has been used since it was adopted in 1966. The present UICC TNM staging approved in 1985 uses a numeric N classification according to the topographic lymph node status. However this lymph node system has some trouble in being easily applied in practice worldwidely. And in new UICC TNM staging system, T1 lesion with lymph node metastasis is classified as stage Ib. But this category was classified as stage III in old TNM staging system according to the general rule of UICC TNM staging. In order to compare the correlation of lymph node classification between topographic lymph node system and numeric classification according to the number of involved lymph node(N0: no lymph node metastasis, N1: 1~3 metastases, N2: > OR =4 metastases) and in order to compare the 5-year-survival rate between UICC TNM staging and authors' modified UICC TNM staging, we analyzed 3,156 patients who received radical gastrectomy with lymph node dissection between 1981 and 1991. Accordance rate between topographic classification and numeric classification was 87.2% in N1 group and 80% in N2 group(correlation coefficient: 0.80, p<0.05). Five year survival rate according to numeric classification(number of involved lymph nodes) was 84.4% for N0 group, 64% for N1 group and 40.3% for N2 group, which are similar to those according to UICC TNM staging system(84.4%, 67.6%, 42.9%, respectively). Also survival curves for each stage in numeric TNM system are also comparable to those for each stage in UICC TNM system. In conclusion, we would like to propose a modified TNM system with a numeric N classification (according to the number of involved lymph nodes) because of its reliability and easy applicability, and also propose that T1 lesion with lymph node metastasis would be incorporated in to stage IIa, instead of stage Ib, in consideration of the general rule of UICC TNM and similarity in the survival rate.