Abstract: Objective To investigate the pattern of lymph node metastasis and analyze prognostic factors of Siewert type Ⅱ adenocarcinoma of esophagogastric junction (AEG). Methods The retrospective case-control study was conducted. The clinicopathological data of 368 patients with Siewert type Ⅱ AEG who were admitted to Tianjin Medical University Cancer Institute and Hospital from June 2010 and November 2015 were collected. There were 323 males and 45 females, aged from 35 to 80 years, with an average age of 64 years. Of 368 patients, 209 underwent left transthoracic surgery, 112 underwent thoracoabdominal surgery, and 47 underwent Ivor-Lewis surgery. Observation indicators: (1) total lymph node metastasis and metastasis of various lymph node stations; (2)follow-up and survival; (3)prognostic factors analysis; (4) influencing factors affecting thoracic lymph node metastasis. Follow-up using outpatient examination and telephone interview was performed to detect survival of patients up to November 2018. Measurement data with skewed distribution were represented as M (range). Count data were represented as absolute number or percentage. The survival time and rate were calculated using the Kaplan-Meier method. The univariate and multivariate analyses were done by the COX proportional hazard model. Results (1) Total lymph node metastasis and metastasis of various lymph node stations: the total lymph node metastasis rate was 66.58%(245/368) in 368 patients. The metastasis rates of abdominal lymph nodes, thoracic lymph nodes, lower mediastinal lymph nodes, and upper mediastinal lymph nodes were 65.49%(241/368), 12.77%(47/368), 12.23%(45/368), and 1.09%(4/368), respectively. The order of metastasis rate of various lymph node stations from high to low was 51.99%(170/237) of No.7 left gastric artery, 34.23%(89/260) of No.1 right paracardial region, 33.88%(83/245) of No.2 left paracardial region, 28.91%(85/294) of No.3 lesser curvature, 27.10%(29/107) of No.11 splenic artery, 19.75%(16/81) of No.9 celiac trunk, 15.25%(36/236) of No.E8Lo lower paraesophageal region, 11.94%(16/134) of No.4 greater curvature, 11.76%(6/51) of No.E8M middle paraesophageal region, 11.11%(10/90) of No.8 common hepatic artery, 4.65%(4/86) of No.E9L left inferior pulmonary ligament and 3.39%(2/59) of No.E7 subcarinal region. (2) Follow-up and survival: of the 368 patients, 309 were followed up for 1-103 months, with a median follow-up time of 38 months. The survival time of 309 patients was 0.7-101.9 months, and the median survival time was 35.9 months. During the follow-up, the postoperative 1-, 2-, 3-year overall survival rates were 85.9%, 68.6%, and 58.7%, respectively. (3) Prognostic factors analysis. Results of univariate analysis showed that tumor differentiation degree, presence of thoracic lymph node metastasis, number of metastatic lymph nodes, T staging, tumor diameter, and length of esophageal invasion were associated factors affecting prognosis of patients (χ2=8.776, 26.582, 46.057, 18.679, 22.460, 9.158, P<0.05). Results of multivariate analysis showed that presence of thoracic lymph node metastasis, number of metastatic lymph nodes, T staging, and tumor diameter were independent influencing factors for prognosis of patients ［odds ratio (OR)=1.699, 1.271, 1.422, 1.238, 95% confidence interval: 1.102-2.621, 1.019-1.481, 1.090-1.856, 0.971-1.481, P<0.05］. (4) Influencing factors affecting thoracic lymph node metastasis: results of univariate analysis showed that tumor diameter, length of esophageal invasion, number of lymph lodes harvested in thorax were related factors for thoracic lymph node metastasis (χ2=5.129, 43.140, 10.605, P<0.05). Results of multivariate analysis showed that length of esophageal invasion ≥2 cm, number of lymph lodes harvested in thorax ≥4 were independent risk factors for thoracic lymph node metastasis (OR=6.321, 1.097, 95% confidence interval: 2.982-13.398, 1.026-1.173, P<0.05). Conclusion Lymph node metastasis of Siewert type Ⅱ AEG spreads two regions, mainly at abdominal lymph nodes, followed by the thoracic lymph nodes. Presence of thoracic lymph node metastasis, number of metastatic lymph nodes, T staging, and tumor diameter are independent influencing factors for prognosis of patients. Presence of thoracic lymph node metastasis indicates poor prognosis of patients. Length of esophageal invasion ≥2 cm and number of lymph lodes harvested in thorax ≥4 are independent risk factors for thoracic lymph node metastasis.