Characteristics of lymph node metastasis and prognostic analysis of Siewert type Ⅰ adenocarcinoma of esophagogastric junction

Objective:To analyze the characteristics of lymph node metastasis and prognostic factors of Siewert type Ⅰ adenocarcinoma of esophagogastric junction (AEG).
Methods:The retrospective casecontrol study was conducted. The clinicopathological data of 87 patients with Siewert type Ⅰ AEG who were admitted to the Qilu Hospital of Shandong University between January 2008 and May 2011 were collected. All the patients underwent lower esophageal and proximal subtotal gastrectomy via left and posterior thoracic incision. No. 107, 108/110, 109, 111, 112 thoracic lymph nodes and No.1/ 2, 3, 4, 5, 6, 7, 10, 11 abdominal lymph nodes were dissected. All the specimens of lymph nodes were detected by pathological examination. Observation indicators included: (1) lymph node dissection and metastasis, (2) followup and prognosis, (3) indexes of prognostic factors analysis: gender, age, tumor differentiation, depth of tumor invasion, TNM stage and lymph node metastasis, (4) stratified analysis of independent prognostic factors. Followup using telephone interview and outpatient examination was performed to detect the survival of patients up to June 2016. Patients were reexamined by blood biochemistry, ultrasound, barium meal, computed tomography (CT) and gastroscopy (if necessary)every 3 months within 2 years postoperatively and every 6 months after 2 years. Count data were represented as ratio and analyzed using the chisquare test. The survival curve and survival rate were respectively drawn and calculated by KaplanMeier method. The univariate and multivariate analyses were done using the Logrank test and COX regression model, respectively.
Results:(1) Lymph node dissection and metastasis: of the 87 patients with Siewert type Ⅰ AEG, 15 didn′t have lymph node metastasis and 72 had lymph node metastasis, with a metastasis rate of 82.8% (72/87). Metastasis rates of No.107, 108/110, 109, 111 and 112 thoracic lymph nodes were respectively 6.9%(6/87), 27.6% (24/87), 0, 4.6% (4/87) and 0, with a significant difference (χ²=63.301, P<0.05). Metastasis rates of No.1/ 2, 3, 4, 5, 6, 7, 10 and 11 abdominal lymph nodes were respectively 52.9%(46/87), 32.2%(28/87), 10.3% (9/87), 0, 0, 47.1%(41/87), 0 and 0, with a significant difference (χ²=215.096, P<0.05) . Metastasis rates of No.1/ 2 and No.7 abdominal lymph nodes were significantly higher than that of No.3 of abdominal lymph nodes (χ²=7.618, 4.059, P<0.05), and there was no significant difference in metastasis rate between No.1/2 and No.7 abdominal lymph nodes (χ²=0.575, P>0.05). (2)Followup and prognosis: 87 patients were followed up for 17-102 months with a median time of 45 months. The 1, 3, 5year survival rates of 87 patients were 100.0%, 69.0% and 34.5%, respectively. (3) Analysis of prognostic factors: results of univariate analysis showed that tumor differentiation, depth of tumor invasion, TNM stage and lymph node metastasis were related factors affecting the prognosis of patients with Siewert type Ⅰ AEG (χ²=7.565, 7.436, 9.377, 6.164, P<0.05). Results of multivariate analysis showed that lowdifferentiated tumor and stage Ⅲ of TNM stage were independent risk factors affecting poor prognosis of patients with Siewert type Ⅰ AEG (RR=0.448, 3.507, 95% confidence interval: 0.27²-0.738, 1.116-11.022, P<0.05). (4) Stratified analysis: median survival time, 1, 3, 5year survival rates were 62 months, 100.0%, 100.0%, 71.4% in 7 patients with highdifferentiated Siewert type ⅠAEG and 52 months, 100.0%, 86.5%, 37.8% in 37 patients with moderatedifferentiated Siewert type ⅠAEG and 36 months, 100.0%, 51.2%, 25.6% in 43 patients with lowdifferentiated Siewert type Ⅰ AEG, respectively, showing a significant difference in survival (χ²=7.565, P<0.05). Median survival time, 1, 3, 5year survival rates were 66 months, 100.0%, 85.2%, 59.3% in 27 patients with Siewert type Ⅰ AEG in stage Ⅰ-Ⅱ of TNM stage and 34 months, 100.0%, 70.0%, 23.3% in 60 patients with Siewert type Ⅰ AEG in stage Ⅲ of TNM stage, respectively, showing a significant difference in survival (χ²＝9.377, P<0.05).
Conclusions:No.107, 108, 110 thoracic lymph nodes dissection and No.1, 2, 3, 7 abdominal lymph node dissection should be emphasized. Lowdifferentiated tumor and stage Ⅲ of TNM stage are independent risk factors affecting poor prognosis of patients with Siewert type Ⅰ AEG.