Relationship between metastatic rate and amount of lymph nodes and prognosis of gastric cancer]

to investigate the relationship between metastatic rate and amount of lymph nodes and prognosis of gastric cancer.The clinical data of 672 patients of gastric cancer with 22.7 regional metastatic lymph nodes on average were analyzed retrospectively. The patients were divided into 3 groups according to the TNM staging system (1997, 5th edition): pN0 (without metastatic lymph node), pN1 group (with 1-6 metastatic lymph nodes), pN2 group (with 7-15 metastatic lymph nodes), and pN3 group (with more than 215 metastatic lymph nodes), or into 4 groups according to the lymph node metastasis rate: rN0 group (without metastasis of lymph node), rN1 group (with a lymph node metastasis rate 0 < 10%), rN2 group (with a lymph node metastasis rate of 10%-30%), and rN3 group with a lymph node metastasis rate > 30%). The 5-year survival rates of different groups in these 2 classification systems and the relationship between metastatic rate and amount of lymph nodes and prognosis of gastric cancer were analyzed.According to the lymph node metastasis grading system there were 93 patients in the pN0 group, 201 in the pN1 group, 108 in the pN2 group, and 32 in the pN3 group with the 5-year survival rates of 90.3%, 65.2%, 37.0%, and 18.9% respectively (chi(2) = 12.56, P < 0.01). According to the lymph node metastasis system 93 patients were in the rN0 group, 183 in the rN1 group, 92 in the rN2 group, and 66 in the rN3 group, with the 5-year survival rates of 90.3%, 69.9%, 45.7%, and 10.6% respectively (chi(2) = 14.38, P < 0.01). If the cases in the same pN group were re-divided according to the lymph node metastasis rate, there were significant differences in the 5-year survival rate among the new rN groups (chi(2) = 5.26, P = 0.21), and there was a great difference in the distribution of prognosis among different groups. However, if the cases in the same group rN group were re-divided according to the amounts of metastatic lymph nodes, there was no significant difference in 5-year survival rate among different new pN groups (chi(2) = 0.14, P = 0.932). Multivariate COX model analysis showed that the influencing factors of the prognosis were rN grading, pN grading, infiltration depth of cancer, gross type, and size of the cancer, arranged according to the degree of closeness (P < 0.05); lymph nose metastasis rate was closely related with the size, infiltration depth, and gross type of the cancer (P < 0.05). In the same metastasis rate, the 5-year survivals rate decreased along with the increase of the amount of metastatic lymph nodes, and vice versa (chi(2) = 8.22, P = 0.004; chi(2) = 4.52, P = 0.033).The staging system based on metastatic lymph node rate is more predictable the number of metastatic lymph nodes for the prognosis of gastric cancer.