Siewert Type I and II Esophageal Adenocarcinoma (EAC): CT, PET-CT, EUS Sensitivity / Specificity for the Assessment of Lymph Node Metastases (LNM) in Groups of Thoracic and Abdominal Lymph Nodal Stations

Esophageal adenocarcinoma (EAC) is a disease with poor overall prognosis and rising incidence in western countries. In patients without organ metastases, therapy is currently based on surgery with or without neoadjuvant therapy; indication for primary surgery is reserved to clinical TNM stages 0-IIa, whereas a multimodality approach is more suitable for clinical TNM stages IIb-III. The operation comprises the resection of distal esophagus and proximal or total gastrectomy. Two field lymphadenectomy is generally recommended, but the extent of lymphadenectomy is among the controversial issues, as extensive removal of nodes may cause significant morbidity and its effect on survival in addition to neoadjuvant therapy is not clear. Current guidelines are based on the 7th edition of AJCC & UICC TNM classification, which stages lymph node status (N) according to the number of metastatic nodes, but do not consider the specific anatomic stations of regional nodes. EAC subtypes are known to demonstrate different metastatic nodal patterns of spread. They may be classified with the Siewert's classification according to the position of the tumor with respect to the esophago-gastric junction (EGJ), or according to histologic parameters like the presence/absence of intestinal metaplasia in the esophagus and stomach. Siewert Type I EAC, which fairly corresponds to the Barret's like type according to the presence absence of intestinal metaplasia, spreads more likely to the thoracic nodal stations, while Siewert Type II and the pyloric like type, do spread more frequently to the perigastric and celiac stations. Therefore, an increasing interest is emerging for preoperative mapping of lymph nodes metastases in order to tailor surgery according to metastatic patterns.

The majority of studies aiming to assess the accuracy of N staging with clinical methods generally refer to the global evaluation of regional nodes according to the 7th edition of staging descriptors. Studies reporting specific data on the clinical staging assessment of specific thoracic and abdominal lymph nodal stations are few, diagnostic tests and results are not uniform, interpretation and comparison of data within reports is not immediate.