Lymph node metastases in middle and upper mediastinum of Siewert type II adenocarcinoma: A real-world retrospective study

Objective: To explore whether the upper and/or middle mediastinal nodes (UMMN) should be dissected in Siewert type II adenocarcinoma (AC) according to the incidence of lymph node metastasis. Additionally, to investigate the association between the length of esophageal involvement (LEI) and the UMMN metastases. Methods: A cohort with Siewert type II AC who were operated on by a surgical team that routinely treated esophagogastric junction (EGJ) tumors with esophagectomy and extended lymphadenectomy were assessed retrospectively. The primary endpoint of the research was the metastasis rate of UMMN. Results: A total of 94 patients with EGJ tumor from July 2018 to September 2022 were enrolled. Station 106recR (6.4%, 6/94) was the only station among upper mediastinal nodes (UMN) that presented positive nodes. Middle mediastinal nodes (MMN) metastases of station 107, 109 and station 108 were 2.1% (2/94) and 5.0% (4/80), respectively. Among the 11 patients with MMN or UMN metastases, 63.6% (7/11) had lesser than seven metastatic nodes, and 54.5% (6/11) had a pathological N stage <= 2. LEI >3 cm (p = 0.042) showed a higher risk for MMN metastases in univariable logistic analysis. However, no independent risk factor for mediastinal node metastases was detected. Conclusion: This study demonstrated that the incidence of positive MMN and UMN is relatively low in resectable Siewert type II AC, which indicated that it is not necessary to perform a routine dissection upon these stations. LEI >3 cm might be associated with higher risk for mediastinal node metastasis. Certain patients could benefit from extended lymphadenectomy since most of the patients with positive MMN or UMN have a limited number of metastatic nodes.