Pathological Approach for Surveillance of Ulcerative Colitis-associated cancer:Usefulness of Immunohistochemistry for p53

The patients with long-standing ulcerative colitis( UC) have a high-risk of neoplastic lesions in the colonicmucosa. The UC-associated neoplastic lesion is difficult to detect by endoscopic examination or diagnosehistologically. In the present study, we aimed to clarify whether immunohistochemistry for p53 is useful todiscriminate the UC-associated neoplasia from inflammed regenerating epithelium. Tissue samples were obtainedfrom colorectomy specimens from 20 patients with long-standing UC (range 6-29 years). The surfaceof microstructure of the tissues was observed by stereomicroscopy, and the sections were examined usingimmunohistochemistry for p53. All of T2-4 carcinomas were detectable by endoscopic examination beforesurgery, whereas considerable number of dysplasias (52.5%), Tis carcinomas (33.3%), and T1 carcinomas(60.0%) were undetectable. Fifty-three of 67 UC-associated neoplastic lesions (79.1%) were of flat-typemacroscopically. The detection rate of flat-type neoplasias( 45.3%) was significantly lower than that of protrudingones (100%). The positivity of p53 overexpression was 0 % in UC-II, 52.5 % in UC-III, and 70.4 %in UC-IV, respectively. UC-II lesions had lower positivity of p53 overexpression than UC-III( P=0.027) or-IV lesions( P=0.003). Immunohistochemical analysis of p53 protein is useful to discriminate the UC-associatedneoplasia from inflammed regenerating epithelium.