Outcomes and precautions of endoscopic submucosal dissection for undifferentiated-type early gastric cancer.
OBJECTIVE
Since the development of techniques for endoscopic submucosal dissection (ESD), the indication range of endoscopic resection (ER) has been extended in early gastric cancer (EGC) treatment. For undifferentiated-type EGC, tumors with an intramucosal depth of invasion, no ulceration and a diameter of 20 mm or less were included in the expanded indications for ER in the Japanese Gastric Cancer Treatment Guidelines 2010. Nonetheless, because of difficulty in detecting lesions that meet the criteria for ER, the number of endoscopically resected cases of undifferentiated-type EGC is less than that of differentiated-type EGC.


METHODS
We retrospectively investigated the outcomes of ESD in 38 patients with 40 lesions of EGC in which the dominant pathological type was confirmed to be undifferentiated (signet ring cell carcinoma, poorly differentiated adenocarcinoma, mucinous adenocarcinoma) on histological examination of resected specimens.


RESULTS
Margin involvement and submucosal infiltration were common noncurative factors. Precise evaluation of the area and depth of lesions is a problem to be solved. Among a total of five patients with involved or uncertain horizontal margins, one of two patients who underwent additional surgery had residual cancer, and one of three patients who were observed had recurrence.


CONCLUSIONS
Undifferentiated-type EGC with a positive horizontal margin may relapse after ESD. It is therefore essential to precisely evaluate the area of the lesion and to perform resection with an adequate safety margin to decrease the risk of recurrence.
Kanagawa Cancer Center, Department of Gastroenterology, Nakao 2-3-2, Asahi-ku, Yokohama City, Yokohama 241-8515, Japan.
Yasuhiro
Y
Inokuchi
Kanagawa Cancer Center, Yokohama, Japan.
Maki
M
Kobayashi
Kanagawa Cancer Center, Yokohama, Japan.
Kana
K
Kudo
Kanagawa Cancer Center, Yokohama, Japan.
Hiroaki
H
Yamada
Kanagawa Cancer Center, Yokohama, Japan.
Shuntaro
S
Inoue
Kanagawa Cancer Center, Yokohama, Japan.
Ken
K
Nishimura
Kanagawa Cancer Center, Yokohama, Japan.
Norisuke
N
Nakayama
Kanagawa Cancer Center, Yokohama, Japan.
Osamu
O
Motohashi
early gastric cancer (EGC); endoscopic resection (ER); endoscopic submucosal dissection (ESD); undifferentiated-type