Early Gastric Cancer

Early gastric cancer is the concept covering carcinomas confined between the mucous and submucous membranes, regardless of tumor size or metastases to the lymph nodes (D Fig. 14), as distinct from so-called advanced cancer growing into the underlying layers of the wall [208]. Marked macroscopic changes in the mucosa are normally absent, except for decreased motility and smoothed-down surface ulcers [104, 106]. This differentiation is explained by substantial deviations in the prognosis of these two groups of carcinomas. The term »early« gastric cancer is not synonymous with »intramucosal cancer«, in situ carcinoma, or superficial spreading carcinoma.

The clinical importance of this form of cancer depends on the longer postoperative survival (about 90%) compared with other cancers of the stomach. Early gastric carcinoma can exist inside the mucous membrane without appreciable growth for about a year, but at its later stages it grows rapidly. There is evidence that early cancer progresses into advanced cancer during 37 months on average. Resection of the stomach at the early stage of the tumor therefore

D Fig. 14. Fragment of a microspecimen of gastric mucosa. Complexes of poorly differentiated adenocarcinoma invading proper muscular coat of the mucous membrane and growing into the submucous layer. Hematoxylin and eosin, x50

guarantees a good prognosis in most cases. Prognosis of early gastric cancer remains good even if the patient is operated on later than in 6 months after the diagnosis was established. In a 10-year period, gastric cancer evolved into the advanced form in only 51% of patients operated on for early cancer [206, 252, 264, 265].

The macroscopic classification of early gastric cancer that is currently used worldwide was proposed in 1962 by the Japanese Gastroenterological Endoscopic Society [153]. In this classification, gastric cancer is divided into the following three major types (► see Scheme 4):

™ Type I protruded cancer, characterized by 0.025-0.15 cm thick mucosa (twice as thick as the surrounding normal mucosa) ™ Type II superficial cancer, further subdivided into three subtypes:

- Type IIa slightly elevated tumor

- Type IIb flat, the rarest tumor, especially characteristic of poorly differentiated adeno-carcinoma and often preceding depression or ulceration of the mucous membrane

- Type IIc slightly depressed tumor, which may have signs of scarred (uls) or existing superficial ulcer (ul) with folds converging toward it (conv); these details are parenthesized

™ Type III distinctly excavated tumor; the lesion is characterized by penetration to the sub-mucous membrane, the tumor tissues being detectable only at the ulcer edges

Combined types include several versions, such as IIa +IIc, IIc + IIa, I + IIc, and IIc + III. With IIa + IIc the changes are characterized by protruding, circular, slightly elevated edges around the central depression, at the level of the normal surrounding mucous membrane. With IIc + IIa - a macroscopic version of early carcinoma - the depression corresponding to IIc is often surrounded by slightly elevated mucosa, represented at the histological level by the glands lined with reactive and hyperplastic epithelium. In those cases where the surrounding mucosa is elevated only slightly, type IIa is often disregarded.

D Fig. 14. Fragment of a microspecimen of gastric mucosa. Complexes of poorly differentiated adenocarcinoma invading proper muscular coat of the mucous membrane and growing into the submucous layer. Hematoxylin and eosin, x50

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