Due to the poor prognosis of advanced gastric cancer, it is well acknowledged that early diagnosis is the most important goal in the approach to gastric cancer. In 1970 Corres et al. reported that a close correlation existed between the occurrence rate of gastric cancer and the prevalence rate of chronic atrophic gastritis or intestinal metaplasia of the gastric mucosa. The purpose of this study is to define the significance of intestinal metaplasia as a precancerous lesion by comparing the proliferative potentials of intestinal metaplasia with that of cancer tissue and normal gastric mucosal tissue. This was accomplished immunohistochemically by measuring and comparing the amount of PCNA protein found in the cancerous tissue, intestinal metaplastic lesions and normal mucosa from the resected samples of gastric cancer patients. We examined resected samples of 86 gastric cancer patients who had been operated on between July 25 and September 23 of 1992, and selected samples of 89 cancerous tissue, 60 intestinal metaplasia tissue and 60 normal mucosa. Each tumor sample was investigated on the histological classification(WHO, Lauren, and Ming classification), degree of mucosal invasion, existence of tumor thrombus and degree of differentiation. PCNA staining was made according to Streptavidin-biotin method. The number of stained cells converted to the percentage of the total number of cells was defined as the PCNA labeling index(LI). Statistical analysis was performed with the Student t-test and ANOVA test by SAS program. Overall, there was no significant difference between the PCNA index of cancer(l6.0%) and intestinal metaplasia(12.6%) with p=0.055, but a significant difference existed between intestinal metaplasia and normal mucosa with an index of 12.6% and 7.42%, respectively(p =0.013). There were na significant differences found between early and advanced cancer(p =0.620). PCNA index was higher with lymph node metastasis than without metastasis in advanced gastric cancer(p=0.009). There were no differences in the LI value in degree of differentiation, tumor thrombi or the Lauren and Ming classifications(p>0.05). PCNA index was higher in the middle and lower zone of the glands of the intestinal metaplasia than normal mucosa. (p=0.001)From the current results, the proliferation potential of peritumoral intestinal metaplasia was found to be higher than normal tissue, and we believe that this lesion should be investigated further as a precancerous lesion. Also, we find the PCNA labeling index to be a useful method as an objective guide for these further investigations.
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