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Siewert classification, one of the most widely used classifications today for AEG, was come up by Siewert
[6]
in 1987 . In this classification, AEG was defined as the tumor whose epicenter located within 5 cm oral
[7]
and aboral of the esophagogastric junction . Siewert type I refers to the tumor whose epicenter located
1-5 cm above the EGJ, and it is usually regarded as esophagus cancer. Siewert type II tumor is considered
as true AEG with a center within 1 cm above and 2 cm below EGJ. Siewert type III, with whose center located
2-5 cm below the EGJ, is treated as gastric cardia tumors. Because AEG has unusual oncology behavior and
characteristics, the treatment for type II remains controversial. The aim of this commentary is to introduce
the surgical strategies for type II AEG in recent years.

OPTIMAL SURGICAL APPROACH FOR SIEWERT TYPE II AEG
For advanced AEG, surgery remains predominant treatment because of the possibility of lymph node
involvement. The appropriate surgical approach should take a lot into consideration including oncology
safety, lymph node dissection and resection margin involvement. In Japan, no matter which type of AEG
is treated by upper gastrointestinal surgeons. However, in China, gastric cancer belongs to abdominal
surgery, and esophagus cancer belongs to thoracic surgery. For Siewert type II AEG, transthoracic and
transhiatal are two major surgical approach. Different surgeons have different opinions on surgical
approach.

The Japan Clinical Oncology Group (JCOG) conducted a randomized controlled multicenter clinical trial
in Japan (JCOG9502). 167 patients with cancer of Siewert type II or III were enrolled from 27 hospitals in
japan and randomly assigned to abdominal transhiatal approach (TH) or left thoracoabdominal (LTA).
The aim of this trial was to explore whether LTA, compared with TH, could prolong the overall survival.
The 5-year overall survival was 52.3% and 37.9% in the TH group and LTA group, respectively, but the
[8]
morbidity was worse in LTA than TH . Subgroup analyses showed no survival benefit for Siewert II
patients in LTA group. Moreover, with respect of six selected major complications (pancreatic fistula,
abdominal abscess, pneumonia, anastomotic leak, empyema thoracis and mediastinitis), the incidence was
significantly higher following the LTA than the TH group: 41% vs. 22% (P = 0.008). And there were two
[9]
treatment-related death in LTA group . Therefore, LTA approach is not recommended for Siewert type II
AEG with the length of esophagus invasion ≤ 3 cm.

Another trial focused on the best approach for esophageal carcinoma. It randomly assigned 220 patients
with adenocarcinoma of mid-to-distant esophagus or adenocarcinoma of the gastric cardia involving
the distal esophagus to transhiatal esophagectomy (THE) or right transthoracic esophagectomy (TTE,
Ivor-Lewis) with extended lymphadenectomy. Ivor-Lewis is a right transthoracic surgical approach for
[10]
distal esophagus cancer, which was introduced by Lewis in 1946 . And this approach was widely used
in western countries. This approach has two procedure which includes gastrectomy and abdominal
lymphadenectomy for stage I, then a right thoracotomy with esophageal resection and peri-esophageal
lymphadenectomy for stage II. Ivor-Lewis was associated with more in-hospital morbidity than transhital.
After transhiatal and transthoracic resection, 5-year survival was 34% and 36% (P = 0.71), respectively.
Although no statistically difference founded among groups, there was a trend toward improving long-
term survival at five years with Ivor-Lewis approach. In subgroup analysis based on Siewert classification,
a 5-year survival benefit of 14% was found in transthoracic group for Siewert type I (51% vs. 37%, P = 0.33)
than transhital group [11,12] , which indicated that Ivor-Lewis may have no benefits for type II AEG. It may
be related to TTE could gain more involved lymph nodes than THE in type I AEG. Recently a single
center reviewed 242 Siewert type II AEG retrospectively, of whom 56 (23.1%) underwent thoracoabdominal
esophagectomy (TAE) and 186 (76.9%) had a transhiatal extended gastrectomy (THG). No difference in
morbidity (P = 0.197) and mortality (P = 0.711) were observed, including anastomotic leakages (P = 0.625)
and pulmonary complications (P = 0.494). And the number of resected lymph node and rate of R0 resection