Study on the histological occurrence of UC-associated cancer and dysplasia

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Ulcerative colitis (UC) associated cancer or dysplasia is characteristic as follows : (1) The morphological status is plaque, (2) Multiple lesions occur, (3) One lesion has another lesion of different atypia around it. Generally the character of a cancer originates from genetic change. Accordingly it is expected that the genetic changes are different between sporadic colorectal cancers and UC-associated cancers.In the study in 1993, we analyzed K-ras mutation. The frequency of K-ras mutation was 60-70% in sporadic colorectal cancers and adenomas. But that was about 10% in UC-associated cancers or dysplasias.In the study in 1994, we analyzed p53 abnormality. We investigated immunohistochemically p53 protein expression of the specimens in paraffin blocks. p53 mutation correlates with p53 protein overexpression. Our data showed p53 protein overexpression was 89% in invasive carcinoma, 70% in high-grade dysplasia, 57% in low-grade dysplasia, but 0% in adenoma, indefinite for dysplasia and nigative for dysplasia. These data suggest that p53 expression is an objective marker not only to confirm a tumor but also to differ adenoma from dysplasia indicative of invasive carcinoma.