Images of Early Gastric Cancer

Introduction

The importance of detecting early gastric cancer (EGC) is to allow treatment of the condition using minimally invasive surgery and enable patients with gastric cancer to maintain a good quality of life. Gastric cancer arises from the mucosal layer of the gastric wall and successively invades the submucosal layer, muscularis propria, subserosa, and serosa. The depth of tumor invasion is classified from T1 to T4 according to the TNM classification (Table [1]). Early gastric cancer is defined as tumor invasion of the mucosa or submucosa (T1), without regard to lymph-node metastasis. The macroscopic type of gastric cancer is classified as types 0 to 5, based on the Borrmann classification of gastric cancer (Figure [1]) (Table [2]) [1]. According to a report by the national registry for gastric cancer in Japan, the incidence of lymph-node metastasis from T1 early gastric cancer was 149 of 1686 cases (8.8 %). The incidence of lymph-node metastasis of mucosal cancer, in which tumor invasion is limited to the mucosal layer, was 11 of 891 (1.2 %), and that of submucosal cancer, in which tumor invasion extends to the submucosal layer, was 138 of 795 (17.4 %) [2].

Table 1 Depth of tumor invasion T1 Tumor invasion of the mucosa or submucosa T2 Tumor invasion to the muscularis propria or subserosa T3 Tumor penetration of the serosa T4 Tumor invasion of adjacent structures

Table 2 Macroscopic types of early gastric cancer Type Characteristics 0 Superficial, flat tumors with or without minimal elevation or depression 0 I Protruding type 0 IIa Superficial elevated type 0 IIb Flat type 0 IIc Superficial depressed type 0 III Excavated type 1 Polypoid tumors, sharply demarcated from the surrounding mucosa, usually attached on a wide base 2 Ulcerated carcinoma with sharply demarcated and raised margins 3 Ulcerated carcinoma without definite limits, infiltrating into the surrounding wall 4 Diffusely infiltrating carcinoma in which ulceration is usually not a marked feature 5 Unclassifiable carcinoma that cannot be classified into any of the above types

Figure 1 The macroscopic types of superficial flat tumor, with or without minimal elevation or depression.

Endoscopic mucosal resection (EMR) is justifiably regarded as the appropriate treatment for mucosal cancer. The natural course of EGC in 56 cases has recently been described. Over a period of 6 -137 months, 20 lesions remained in the early stage, while 36 progressed to the advanced stage. The cumulative 5-year risk of progression to the advanced stage was 63 % [3].

It is a great honor for Japanese endoscopists to present various pictures of early gastric cancer in this journal.
Ryuzo Murai

References

• 1 Japanese Gastric  Cancer Association. Japanese classification of gastric carcinoma. 2nd English ed. Tokyo; Kanehara 1998
• 2 Ohshiba S, Ashiba K, Tanaka M. et al . Curative endoscopic resection of early gastric cancer: the possibility of extending its indications.  Stomach Intest (Tokyo). 1993;  28 87-98
• 3 Tsukuma H, Ohshima A, Narahara H. et al . Natural history of early gastric cancer: a non-concurrent, long-term, follow-up study.  Gut. 2000;  47 618-621