MICROSATELLITE INSTABILITY IN NONNEOPLASTIC MUCOSA FROM PATIENTS WITHCHRONIC ULCERATIVE-COLITIS

Microsatellite instability (MIN) has been detected in many cancer type s; however, recently we also observed it in the nonneoplastic but infl ammatory setting of pancreatitis. Consequently, we sought to examine w hether MIN was present in another inflammatory condition, ulcerative c olitis (UC). MIN was found in 50% of UC patients whose colonic mucosa was negative for dysplasia, 46% of those with high-grade dysplasia, an d 40% of those with cancer but in none of the nine ischemic or infecti ous colitis controls (P < 0.03). Thus, UC patients may have MIN within mucosa that has no histological evidence of neoplastic change. MIN in this setting may reflect the inability of DNA repair mechanisms to co mpensate for the stress of chronic inflammation, and may be one mechan ism for the heightened neoplastic risk in UC.