Esophagastric Junction Cancers (AEG)
Tumors of the esophagogastric junction should be classified not only according to the system with regards to tumor penetration (T stage), presence of lymph nodes (N stage) and distant metastases (M stage), also with regards to tumour location, namely oesophageal versus gastric extent. This has significant consequences with regards to surgical strategy. Initially, the Siewert classification 1 provided a good overview and was based on the location of the tumor center.
Although this assessment generates some variances in assessment (e.g. in cases with a tumor center in the cardia, e.g. deep ulcer, but a long extension into the esophagus), it was a useful approximation of the tumor location with regards to further management. For documentation especially in long tumors, a series of images prograde and in inversion or better a video sequence has to be taken to enable proper classification. Such variations are shown in the following schematic drawing:
The Siewert classification is not included in the TNM system, there is only allocation to either esophageal or gastric cancer. Thus, the TNM system has incorporated the location and modified it again in its latest version from 20162. As outlined in a recent review3, „the definition of cancer location cL has changed from the position of the upper edge of the cancer (7th edition) to its epicenter (8th edition), both referenced to distance from the incisors. Clinically, the epicenter is determined from upper and lower border measurements, which also provide cancer length. For treatment planning, it is critical to know the upper border for cancers of the cervical and upper thoracic esophagus and the lower border for cancers of the lower thoracic esophagus and EGJ“.
In the latest TNM classification version2, the lower margin of definition of extent of esophageal cancer has been changed from 5 cm to 2 cm, i.e. a tumour the epicenter of which is within 2 cm of the oesophagogastric junction and also extends into the esophagus is classified and staged using the oesophageal scheme. Cancers involving the esophagogastric junction (EGJ) whose epicenter is within the proximal 2 cm of the cardia (Siewert types I/II) are therefore to be staged as esophageal. Cancers whose epicenter is more than 2 cm distal from the EGJ will be staged using the Stomach Cancer TNM and Stage even if the EGJ is involved.
Schematic examples in the following:
Siewert type I (Barrett cancer)
Siewert type II (cardia cancer)
Figure 7: Large flat and ulcerated cancer at the cardia (left), in inversion seen as tumorous ring around the cardia (right); since this ring extends less than 2 cm into the stomach, classified as esophageal cancer
Figure 8: Ulcerated tumor in the cardia extending 3-4 cm into the distal esophagus (left), also seen as tumorous thickening of the gastric mucosa in cardia and fundus on inversion (right); the epicenter of the tumor however is at the eg junction (i.e. within 2 cm of eg junction), and therefore also classified as esophageal cancer (TNM)
Figure 9: Flat and only slightly irregular tumor area in the cardia with indistinct margins, measuring about 2-3 cm; again, the epicenter of the tumor however is at the eg junction (i.e. within 2 cm of eg junction), and therefore also classified as esophageal cancer
Figure 10: Very discrete early cardia cancer, just manifested as a slight thickening of folds (upper left) with full insufflation of the stomach; the right upper picture shows a fully inflated cardia within a hiatal hernia with only slight superficial irregularities and vascular changes, hard to detect on this image. Only with a cap, the structural irregularities and some vulnerability become obvious (lower left), while the full extent of a grossly irregular surface pattern is only manifest on narrow band imaging, magnification, under water endoscopy and less insufflations (lower right). Also this cancer is classified esophageal according to TNM.
Siewert type III
- Siewert JR, Holscher AH, Becker K, et al. [Cardia cancer: attempt at a therapeutically relevant classification]. Chirurg 1987;58:25-32.
- James D. Brierley (Editor) MKGE, Christian Wittekind (Editor) TNM Classification of Malignant Tumours, 8th Edition. Wiley-Blackwell 2016.
- Rice TW, Patil DT, Blackstone EH. 8th edition AJCC/UICC staging of cancers of the esophagus and esophagogastric junction: application to clinical practice. Ann Cardiothorac Surg 2017;6:119-130.