Abstract: Objective To investigate the relationship between the maximum tumor diameter (MTD) and lymph node metastasis, cancer cell invasion and differentiation degree,and the effects of MTD on the survival of gastric cardia adenocarcinoma(GCA), and to improve TNM staging of GCA. Methods MTD was examined in resected GCA specimens from 4 826 cases with GCA. All of 1 756 cases were follow-up by interview and questionnaires at home and (or) telephone communication.Kaplan-Meier,Log-rank test and Cox proportional hazard model was used to analyze the difference of survival. Results The mean and the median MTD of 4 826 cases were (5.6±2.3) cm and 5.0 cm (0.5-18.0 cm),respectively.Based on MTD, GCA patients were divided into four groups (MTD＜3 cm, ≥3-6 cm, ≥6-9 cm, ≥9 cm). With MTD increasing, the positive rate of lymph node metastasis, and the invasion depth became incraesed signifi cantly (r=0.254 and 0.102,P<0.05), but differentiation degree decreased gradually (r=0.069,P＜0.05); Furthermore, the fi ve-year survival rate was lower signifi cantly(P＜0.05). It was noteworthy that, even in GCA patients with negative lymph node metastasis, the increased MTD was related to the shorter fi ve-year survival. Cox multivariate survival analysis found that MTD,lymph node metastasis, cancer cell invasion and differentiation degree were independent factors for the prognosis. Conclusion Lymph node metastasis, cancer cell invasion and differentiation degree were independent risk factors for the prognosis of GCA.