ABSTRACT
BACKGROUND: Intestinal metaplasia (IM) type 3 has been suggested to be associated with gastric cancer of intestinal type. Excess nitric oxide (NO) has been reported to be associated with pathogenesis of various diseases, including gastric cancer. This study measured isoform nitric oxide synthase (iNOS) expression immunohistochemically to examine the possible involvement of NO in the subtypes of intestinal metaplasia. METHODS: The subjects were 71 male and 35 female cases. To classify the IM subtypes, the specimens were stained with alcian blue pH 2.5/PAS and high iron diamine/alcian blue pH 2.5. The expression of iNOS was assessed by means of immunohistochemical stain using polyclonal anti-iNOS antibody. RESULTS: IM type 1 was diagnosed in 42 cases (39.6%), IM type 2 in 42 cases (39.6%), and IM type 3 in 22 cases (20.8%). As the subject become older, the frequency of IM type 3 increased significantly. The expression of iNOS was increased significantly as the subtype was developed into type 3. However, there was no significant difference in the iNOS expression by the existence of sulphomucin, age, positivity of Helicobacter pylori, or biopsy site. CONCLUSION: Increased expression of iNOS in the IM type 3 suggests that IM type 3 is a possible risk factor for gastric cancer.