Objective To investigate the influencing factors and regularity of inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ adenocarcinoma of esophagogastric junction (AEG).

Methods The retrospective case⁃control study was conducted. The clinicopatho-logical data of 185 Siewert type Ⅱ and Ⅲ AEG patients in two medical centers (113 cases in Changzhi People's Hospital Affiliated to Changzhi Medical College and 72 cases in Heji Hospital Affiliated to Changzhi Medical College) from January 2017 to January 2022 were collected. There were 143 males and 42 females, aged (64±8)years. Patients underwent radical resection of AEG combined with inferior mediastinal lymph node dissection. Observation indicators: (1) clinicopathological charac-teristics of Siewert type Ⅱ and Ⅲ AEG patients; (2) analysis of influencing factors for inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG; (3) regularity of inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was analyzed using the t test. Measurement data with skewed distribution were represented as M(range), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were represented as absolute numbers or percentages, and comparsion between groups was analyzed using the chi-square test or Fisher exact probability. Comparison of ordinal data was analyzed using the rank sum test. Univariate and multivariate analyses were conducted using the Logistic regression model.

Results (1) Clinicopathological characteristics of Siewert type Ⅱ and Ⅲ AEG patients. Pathologic staging as stage Ⅰ, Ⅱ, Ⅲ and Ⅳ, degree of tumor invasion as stage T1, T2, T3 and T4, length of esophageal invasion ≤1 cm, >1 cm and ≤2 cm, >2 cm and ≤3 cm, >3 cm and ≤4 cm were found in 30, 61, 75, 7, 3, 41, 79, 50, 101, 46, 18, 8 cases of the Siewert type Ⅱ and Ⅲ AEG patients without inferior mediastinal lymph node metastasis, respectively, versus 0, 2, 10, 0, 0, 0, 5, 7, 4, 3, 2, 3 cases of the Siewert type Ⅱ and Ⅲ AEG patients with inferior mediastinal lymph node metastasis, showing a significant differences between them (Z=‒2.21, ‒2.49, ‒2.22, P<0.05). (2) Analysis of influencing factors for inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG. Results of univariate analysis showed that pathological staging, depth of tumor invasion and length of esophageal invasion were related factors affecting inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG (odds ratio=2.48, 3.26, 2.03, 95% confidence intervals as 1.02‒6.01, 1.21‒8.80, 1.18‒3.51, P<0.05). Results of multivariate analysis showed that depth of tumor invasion and length of esophageal invasion were independent influening factors affecting inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG (odds ratio=4.01, 2.26, 95% confidence interval as 1.35‒11.96, 1.26‒4.06, P<0.05). The inferior mediastinal lymph node metastasis probability of AEG patients with the length of esophageal invasion >3 cm and ≤4 cm was 9.47 times that of AEG patients with the length of esophageal invasion ≤1 cm. (3) Regularity of inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG. The number of inferior mediastinal lymph nodes including No.110, No.111 and No.112 dissected in 185 patients of Siewert type Ⅱ and Ⅲ AEG were 127, 50 and 27. The number of lymph nodes dissected and the number of metastatic lymph nodes in No.110 and No.111 of patients with length of esophageal invasion ≤1 cm, >1 cm and ≤2 cm, >2 cm and ≤3 cm, >3 cm and ≤4 cm were 69, 4, 42, 4, 4, 1, 12, 4 and 23, 0, 17, 0, 7, 2, 3, 0, respectively. There were significant differences in metastatic lymph nodes in No.110 and No.111 of patients with length of esophageal invasion ≤1 cm, >1 cm and ≤2 cm, >2 cm and ≤3 cm, >3 cm and ≤4 cm (χ²=8.45, 7.30, P<0.05). Of the 185 patients of Siewert type Ⅱ and Ⅲ AEG, the ratio of cases with inferior mediastinal lymph nodes metastasis was 6.49%(12/185). The ratio of inferior mediastinal lymph nodes metastasis in cases with length of esophageal invasion ≤1 cm, >1 cm and ≤2 cm, >2 cm and ≤3 cm, >3 cm and ≤4 cm were 3.81%(4/105), 6.12%(3/49), 10.00%(2/20), 27.27%(3/11), respectively. The ratio of No.110 lymph nodes metastasis in cases with length of esophageal invasion ≤1 cm, >1 cm and ≤2 cm, >2 cm and ≤3 cm, >3 cm and ≤4 cm were 2.86%(3/105), 6.12%(3/49), 5.00%(1/20), 27.27%(3/11), respectively, showing a significant difference among them (χ²=8.26, P<0.05).

Conclusions Depth of tumor invasion and length of esophageal invasion are independent influening factors affecting inferior mediastinal lymph node metastasis in Siewert type Ⅱ and Ⅲ AEG. The rate of inferior mediastinal lymph node metastasis increases with the increase of the length of esophageal invasion.