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Page 4 of 9 Oo et al. Mini-invasive Surg 2019;3:13 I http://dx.doi.org/10.20517/2574-1225.2019.02

compared to surgery. The 5-year overall survival rates were similar in both groups. There was no gastric
cancer related death in each group and the incidence of treatment-related adverse events was similar in
both groups leading the authors to conclude that ESD may be an effective alternative to surgery with
[27]
comparable long-term oncologic outcomes . ESD has a good safety profile with low number of adverse
events reported by many centers [28,29] . According to one comparative study, ESD was associated with much
less adverse events compared to surgery group (10% vs. 17.9%). ESD is a highly skilled procedure mainly
performed in Asian centers and many authors have described a steep learning curve for those performing
ESD especially for GEJ tumours, therefore appropriate training including simulation based practice within
a training framework must be enforced to increase safety and efficacy [30-32] . Based on current evidence, ESD
for superficial early EGJ cancers is feasible and safe with favorable long-term outcomes however further
work is necessary to establish specific resection criteria for ESD of GEJ tumours.

Surgical management of GEJ tumours
There are various surgical strategies for management of GEJ cancers. They include esophagectomy with
partial gastrectomy or extended total gastrectomy with or without thoracotomy. Individualization of the
surgical strategy and adherence to sound oncological principles with aims of radical lymphadenectomy
with negative margins for the resectable GEJ tumours is key in attaining good outcomes. Tumour location
as per Siewert Classification and location of enlarged lymph nodes are critical factors in determining the
surgical strategy.

The pattern and frequency of lymph node metastasis differ according to the epicenter of the tumour
[37]
location and histology [33-36] . Matsuda et al. carried out clinicopathological correlation of surgically
resected GEJ tumours and found that the frequency of mediastinal lymph node metastasis was also found
to be higher in squamous cell carcinoma than adenocarcinoma (46.7% vs. 7.5%).

Regardless of the Siewert classification, the majority of the junctional tumours metastasise to the
perigastric/abdominal regional lymph nodes [36,37] . The frequency of mediastinal lymph node metastasis
differs significantly depending on the Siewert types. The mediastinal lymph node metastasis was only
9% in Type III compared to 30% in Type II and 46% in Type I tumours while abdominal lymph nodes
[35]
metastasis are found to be 51%, 71% and 91% respectively for Type I, II and III tumours . Hence, choice of
surgery and lymphadenectomy need to be tailored according to the epicentre and histology of the tumor.

Siewert type I tumours are considered as lower esophageal tumours with potential lymph node metastasis
to mediastinal and abdominal lymph nodes. Subtotal esophagectomy with partial gastrectomy is considered
to be a superior approach for type 1 tumours. Siewert type 3 tumours are considered proximal gastric
cancer with potential lymph node metastasis to lower mediastinal and abdominal lymph nodes. Extended
total gastrectomy with distal esophagectomy is considered more appropriate for type 3 tumour [15,38-40] .

Siewert type II tumours are true junctional tumours and choice of surgical approach is controversial. In
a retrospective study comparing transmediastinal esophagectomy with partial gastrectomy and extended
total gastrectomy with transhiatal distal esophagectomy, it was demonstrated that the latter was associated
[38]
with fewer post-operative morbidity and mortality without any difference in survival . However, the
subgroup analysis of those patients with R0 resection showed that extended total gastrectomy and not a
transmediastinal oesophagogastrectomy was an independent predictor for long term survival.

There were two phase III randomized control trials which compared two operative strategies for
GEJ cancers [41,42] . In the Dutch Trial, 220 patients with Siewert Type I and II tumours were randomly
assigned to transhiatal esophagectomy (THE) vs. extended transthoracic esophagectomy and en-bloc
[41]
lymphadenectomy (via right thoracic cavity) (TTE) . THE was associated with lower morbidity such as