Objective:To investigate the clinical efficacy of proximal gastrectomy and total gastrectomy in the treatment of Siewert type Ⅱ and Ⅲ adenocarcinoma of esophagogastric junction (AEG).Methods:The retrospective cohort study was conducted. The clinicopathological data of 170 patients with Siewert type Ⅱ and Ⅲ AEG who were admitted to Guangdong Provincial People′s Hospital from January 2010 to December 2018 were collected. There were 125 males and 45 females, aged from 30 to 85 years, with a median age of 64 years. Of the 170 patients, 82 cases undergoing proximal gastrectomy were allocated into the proximal gastrectomy group and 88 cases undergoing total gastrectomy were allocated into the total gastrectomy group. Observation indica-tors: (1) surgical and postoperative situations; (2) follow-up and survival; (3) analysis of prognostic factors. Follow-up was conducted using telephone interview and outpatient examination to detect survival of patients up to December 2021. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Measure-ment data with skewed distribution were represented as M( Q1, Q3) or M(range), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were described as absolute numbers or percentages, and comparison between groups was analyzed using the chi-square test or Fisher exact probability. Comparison of ordinal data was analyzed using the rank sum test. Kaplan-Meier method was used to draw survival curves, and Log-Rank test was used for survival analysis. COX proportional hazard model was used for univariate and multivariate analyses. Variables with P<0.1 in univariate analysis were included for multivariate analysis. Results:(1) Surgical and postoperative situations. Cases with surgical approach as transthoracic or thoraco-abdominal approach, transabdominal approach, the operation time, cases with volume of intra-operative blood loss ≤100 mL or >100 mL, cases with length of proximal margin ≤1.5 cm or >1.5 cm, cases with radical surgery outcome as R 0, R 1, R 2, the number of lymph nodes harvest, cases with anastomotic leakage, cases with anastomotic stricture, cases with incision infection, cases with pleural infection or effusion, cases with abdominal infection or ascites were 61, 21, (211±18)minutes, 46, 36, 44, 38, 73, 6, 3, 15(9,22), 5, 2, 2, 4, 2 in the proximal gastrectomy group, respec-tively. The above indicators were 12, 76, (263±15)minutes, 27, 61, 45, 43, 82, 4, 2, 23(18,32), 4, 1, 3, 1, 4 in the total gastrectomy group, respectively. There were significant differences in the surgical approach, operation time, volume of intraoperative blood loss and the number of lymph nodes harvest between the two groups ( χ2=63.94, t=-25.50, χ2=11.19, Z=-5.62, P<0.05). There was no significant difference in the length of proximal margin or radical surgery outcome between the two groups ( χ2=0.11, Z=-0.95, P>0.05) and there was no significant difference in the anastomotic leakage, anastomotic stricture, incision infection, pleural infection or effusion, abdominal infection or ascites between the two groups ( P>0.05). (2) Follow-up and survival. All the 170 patients were followed up for 89(64,106)months. Of the 170 patients, the 5-year overall survival rates were 43.8% and 35.5% of the Siewert type Ⅱ and Ⅲ AEG patients, respectively, showing no significant difference between them ( χ2=0.87, P>0.05). Of the patients with Siewert type Ⅱ AEG, the 5-year overall survival rates were 41.7% and 54.3% in the patients with proximal gastrectomy and the total gastrectomy, respectively, showing no significant difference between them ( χ2=1.05, P>0.05). Of the patients with Siewert type Ⅲ AEG, the 5-year overall survival rates were 31.3% and 37.5% in the patients with proximal gastrectomy and the total gastrectomy, respectively, showing no significant difference between them ( χ2=0.33, P>0.05). The 5-year overall survival rates were 39.0% and 44.2% in the proximal gastrectomy group and the total gastrectomy group, respectively, showing no significant difference between the two groups ( χ2=0.63, P>0.05). Of the patients in TNM stage Ⅰ, stage Ⅱ, stage Ⅲ, the 5-year overall survival rates were 65.3%, 36.3%, 27.1% in the proximal gastrectomy group, versus 83.3%, 48.0%, 39.7% in the total gastrectomy group, showing no signifi-cant difference between the two groups ( χ2=0.02, 1.50, 1.21, P>0.05). (3) Analysis of prognostic factors. Results of univariate analysis showed that pathological N staging, degree of tumor differen-tiation and radical surgery outcome were related factors influencing prognosis of AEG patients ( hazard ratio=1.71, 1.70, 2.85, 95% confidence interval as 1.16-2.60, 1.15-2.50, 1.58-5.14, P<0.05). Results of multivariate analysis showed that pathological N staging and radical surgery outcome were independent factors influencing prognosis of AEG patients ( hazard ratio=1.55, 2.18, 95% confidence interval as 1.05-2.31, 1.18-4.02, P<0.05). Conclusions:There is no significant difference in the prognosis of Siewert type Ⅱ and Ⅲ AEG patients undergoing proximal gastrectomy or total gastrectomy. Proximal gastrectomy can be used for the treatment of advanced Siewert type Ⅱ and Ⅲ AEG.