| [ Summary ] |
Gastric hyperplastic polyps have been shown to have a malinant potential because of the presence of those that exhibit focalized cancers historogically and malingnant changes in follow up cases examined using biopsies. In spite of this, the extremely low incidence of such casesand the rapid decrease in number of hyperplastic polyps the past decade, strongly suggests the minimal significance in relation to gastric premalignancy.
In contrast, gastric adenomas, of which more than 90% display an elevated appearance macroscopically and accompany extensive intestinal metaplasia histologically, appear to be a more specific premalignant lesions than atrophic gastritis alone. About 30% of the 890 adenoma cases endoscopically examined at the National Cancer Center were associated with cancerous changes within the adenomatous lesion or elsewhere in the stomach, suggesting a similar underlying histogenesis of the two neoplasms .In addition, according to the results of our study of 77 lesions, followed up with biopsies for more than 3 years, 14 of the lesions (18%) enlarged in size, and 9 of the 14 cases increased their histological atypism during the follow up period. In addition, 4 cases out of the 9 were diagnosed as malignant more than 5 years after the initial biopsy. These findings may confirm the close relationship between gastric adenoma and carcinoma, but the accuracy of histological diagnosis using extremely small biopsy specimens and the heterogeneity of cellular and/or structural atypism in cancerous lesions may cause problemswith diagnosis, particularly in cases with a "very well differentiatedtubular adenocarcinoma". Endoscopic mucosal resection(EMR) is certainly a worthy procedure to produce an accurate histological diagnosis,particularly for those displaying high risk endoscopic findings. Because thosewith well differentiated adenocarcinoma similar to adenoma histologically have extremely low incidence of submucosal invasion andmetastasis, regardless of their size, they can be cured with full resection using EMR. |