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Takeuchi et al. J Cancer Metastasis Treat 2018;4:38 I http://dx.doi.org/10.20517/2394-4722.2017.83 Page 5 of 9

Primary tumor Sentinel node

Sentinel lymphatic basin

Non-exposed endoscopic wall-inversion surgery (NEWS)

Figure 2. Schema of nonexposed endoscopic wall-inversion surgery (NEWS) with laparoscopic sentinel node mapping and sentinel
lymphatic basin dissection for early-stage gastric cancer

A combination of ESD with laparoscopic SN mapping for early-stage gastric cancer views another desirable
option as a new minimally invasive stomach-preserving treatment. When all SNs are pathologically negative
for metastasis in laparoscopic SN mapping and biopsy, then theoretically, ESD instead of gastrectomy might
be sufficient for the curative resection of cT1 gastric cancer beyond the ESD criteria [20,23] . However, further
studies are needed to certify the reliability of laparoscopic SN mapping with ESD.

Currently, LDG or LTG is frequently employed in patients with early-stage gastric cancer based on the
pathological assessment of primary lesion obtained using ESD in the practice. Until now, whether SN
mapping would be feasible or not even after ESD remains unknown. One of the most important concerns
is that the lymphatic flow from the primary lesion to the original SN might be altered after ESD. However,
a previous study reported that at least the SN basin was not markedly changed by ESD prior to surgery [20,23] .
Laparoscopic limited gastrectomy based on SN mapping and biopsy could be feasible even after ESD.

NONEXPOSED ENDOSCOPIC WALL-INVERSION SURGERY WITH MINIMALLY INVASIVE SN
BIOPSY
In laparoscopic partial gastrectomy, the demarcation line of the primary tumor cannot be identified
accurately because the approach of gastrectomy is usually from the outside of the stomach. Therefore,
a wider resection of the stomach cannot be avoided to prevent a positive surgical margin of primary
tumor site. Recently, a new technique called nonexposed endoscopic wall-inversion surgery (NEWS) has
been developed. The procedure is a full-thickness partial resection of the stomach, which can minimize
the extent of gastric resection using endoscopic and laparoscopic surgeries without transluminal access
designed to resect early-stage gastric cancer. In our ongoing clinical trial, the cases of NEWS with
laparoscopic SN mapping and sentinel basin dissection have been accumulated in cT1N0M0 early-stage
gastric cancer [Figure 2] [24,25] .

In brief, after placing circumferential mucosal markings of primary tumor, ICG was endoscopically
injected into the submucosal layer around the primary lesion to identify the SNs [Figure 3] . The
[24]
SN basin including SNs was dissected, and no metastasis in all SN was confirmed by intraoperative
pathological examinations. After the SN mapping and biopsy, NEWS was performed for the resection