Objective To investigate the clinicopathological characteristics and prognostic factors of Siewert Ⅱ and Ⅲ adenocarcinoma of esophagogastric junction (AEG).

Methods The retrospetcive cohort study was conducted. The clinicopathological data of 399 patients with AEG who were admitted to Peking University People′s Hospital from January 1998 to December 2015 were collected. There were 318 males and 81 females, aged 66(range, 19-87)years. Observation indicators: (1) clinicopathological characteristics of Siewert Ⅱ and Ⅲ AEG; (2) follow‑up and survival; (3) prognostic factors analysis. Patients were followed up by telephone interview and outpatient examination to detect postoperative survival up to December 2018. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was conducted using the t test. Measurement data with skewed distribution were represented as M(range), and comparison between groups was conducted using the Mann‑Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi‑square test or Fisher exact probability. Kaplan‑Meier method was used to draw survival curves and calculate survival rates. Log‑rank test was used for survival analysis. Univariate and multivariate analyses were done using the COX proportional hazard model.

Results (1) Clinicopathological characteristics of Siewert Ⅱ and Ⅲ AEG. Of 399 patients, 198 cases were Siewert Ⅱ AEG and 201 cases were Siewert Ⅲ AEG. There were 130 cases undergoing transthoracic radical AEG surgery, 172 cases undergoing trans-abdominal proximal gastrectomy and 97 cases undergoing transabdominal total gastrectomy. The age, tumor diameter, cases with surgical method as transthoracic radical AEG surgery, transabdo-minal proximal gastrectomy and transabdominal total gastrectomy, the number of positive lymph nodes, cases in tumor TNM stage Ⅰ, Ⅱ, Ⅲ, Ⅳ were (65±10)years, (5.1±2.4)cm, 102, 68, 28, 17(range, 12‒22), 20, 57, 117, 4 for patients with Siewert Ⅱ AEG, versus (62±12)years, (6.3±3.2)cm, 28, 104, 69,18(range, 14‒27), 16, 41, 134, 10 for patients with Siewert Ⅲ AEG, showing significant differ-ences betweeen them (t=2.83, ‒3.82, χ²=66.97, U=17 407.05, 17 532.00, P<0.05). (2) Follow‑up and survival. All 399 patients were followed up for 34(range, 2‒160)months. The 5‑year overall survival rate was 29.3% for patients with Siewert Ⅱ AEG, versus 37.0% for patients with Siewert Ⅲ AEG, showing no significant difference betweeen them (χ²=1.46, P>0.05). The median survival time and 5‑year overall survival rate were 29.0 months 95% confidence interval (CI) as 23.4‒34.6 months and 22.9% for patients undergoing transthoracic radical AEG surgery, 43.0 months(95%CI as 33.9‒52.1 months) and 34.7% for patients undergoing transabdominal proximal gastrectomy, 54.0 months (95%CI as 37.6‒70.4 months)and 44.3% for patients undergoing transabdominal total gastrectomy, showing a significant difference in the survival among the 3 groups (χ²=13.81, P<0.05). Of the 198 Siewert Ⅱ AEG patients, the 5‑year overall survival rate was 24.6% for the 96 patients undergoing transabdominal surgery, versus 35.4% for the 102 patients undergoing transthoracic surgery, showing no significant difference in the survival between them (χ²=3.10, P>0.05). Of the 201 Siewert Ⅲ AEG patients, the 5‑year overall survival rate was 40.0% for the 173 patients undergoing transabdominal surgery, versus 16.1% for the 28 patients undergoing transthoracic surgery, showing a significant difference between them (χ²=11.32, P<0.05). (3) Prognostic factors analysis. Results of univariate analysis showed that surgical method, pathological N staging, patholgical M staging were related factors for prognosis of Siewert Ⅱ and Ⅲ AEG (hazard ratio=0.68, 1.25, 2.18, 95%CI as 0.54‒0.86, 1.15‒1.36, 1.28‒3.73, P<0.05). Results of multivariate analysis showed that transthoracic approach, pathological stage N2‒N3 and pathological stage M1 were independent risk factors for prognosis of Siewert Ⅱ and Ⅲ AEG (hazard ratio=0.64, 1.25, 2.18, 95%CI as 0.51‒0.80, 1.16‒1.35, 1.28‒3.70, P<0.05).

Conclusions Compared with Siewert Ⅲ AEG, Siewert Ⅱ AEG has a smaller tumor diameter, less positive lymph nodes, poorer prognosis. Transthoracic approach is preffered for the Siewert Ⅱ AEG. Transthoracic approach, pathological stage N2‒N3 and pathological stage M1 are independent risk factors for prognosis of Siewert Ⅱ and Ⅲ AEG.