Although the major histologic type in small gastric cancers, less than 10 mm in diameter, is differentiated-type adenocarcinoma (D.Ca), the incidence of D.Ca and that of undifferentiated-type adenocarcinoma (UD.Ca) is almost the same in all early gastric cancers. Histologic conversion from D.Ca to UD.Ca has been speculated, however, a detailed examination of this phenomenon has not yet been performed. Three-hundred and 51 early gastric cancers (D.Ca, 150 (42.7%) lesions; UD.Ca, 93 (26.4%) lesions; and mixed differentiated and undifferentiated type (D&UD.Ca), 108 (30.8%) lesions; tumor size less than 10 mm in diameter; 64 lesions, more than 10 mm, 287 lesions) were examined histochemically with paradoxical concanavalin A type III and high-iron diamine-Alcian blue (pH 2.5), and immunohistochemically with antigastric mucin antibody. The associations between tumor size, tumor differentiation and phenotypic expression of mucin were examined. Regardless of the tumor size, mucin phenotypic expression in the mucosal lesions examined was preserved. Of 47 cancers with a gastrointestinal mucin phenotype (GIM type) or a gastric mucin phenotype (GM type) measuring less than 10 mm, 35 (74.5%) consisted of D.Ca and 12 (25.5%) of both D&UD.Ca and UD.Ca, while of 224 GIM or GM type cancers measuring more than 10 mm, 64 (28.6%) consisted of D.Ca and 160 (71.4%) of both D&UD.Ca and UD.Ca. Differences between these two groups were statistically significant (P < 0.001). Of 15 cancers with an intestinal mucin phenotype (IM type) measuring less than 10 mm, 12 (80.0%) consisted of D.Ca and three (20.0%) of both D&UD.Ca and UD.Ca, and of 50 IM type cancers measuring more than 10 mm, 35 (70.0%) consisted of D.Ca and 15 (30.0%) of both D&UD.Ca and UD.Ca. Differences between these two groups were not statistically significant. These findings suggest that small D.Ca showing gastric mucin expression may transform into UD.Ca during the progression of early gastric cancer.
We report the late results of resection in 281 patients with gastric carcinoma extending to adjacent organs. In 92 without incurable factors (peritoneal dissemination, liver metastasis and widespread nodal involvement) the 5-year survival rate was 36.7 per cent in those treated by gastrectomy and complete removal of the invaded organ. This value is significantly higher than the 17.4 per cent recorded in those undergoing gastrectomy alone or with incomplete removal of the invaded organs (P less than 0.05). In 189 patients with incurable factors, the 5-year survival rates were 5.4 and 2.8 per cent respectively in cases of complete and incomplete excisions. This tendency was similar in patients with a single invaded organ and also in those with plural organ involvement. In potentially curable patients treated by complete excision, the probability of long-term survival was statistically better than that following incomplete excision only when the pancreas was involved (P less than 0.05). We recommend complete excision of invaded organs, irrespective of the number or site of organs involved, provided that there is no evidence of incurable factors.
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