MICROSATELLITE INSTABILITY IS ASSOCIATED WITH THE MACROSCOPIC CONFIGURATION OF NEOPLASMS IN PATIENTS WITH MULTIPLE COLORECTAL ADENOMAS

Background: The management of patients with multiple colorectal adenom as, 10-100 in number, is often troublesome clinically To establish the reasonable management of such cases, genetic backgrounds should be ma de clear. Methods: For a total of 19 adenomas and four carcinomas from four patients with multiple colorectal adenomas, we analyzed genetic instability at four selected microsatellite loci and screened exon 1-4 of the APC gene with special reference to macroscopic configurations of adenomas and carcinomas. Results: RER-positive phenotypes were dete cted in none of 13 protruded type adenomas, two (33%) out of six super ficial elevated type adenomas and two (50%) out of four carcinomas. We detected no mutation of exon 1-4 of the APC gene in any sample. In pa tients with multiple colorectral adenomas, the proportion of superfici al elevated type adenomas exhibiting genetic instability was significa ntly higher than that of protruded type adenomas. Conclusions: The res ults suggested that RER-positive phenotype was an early event in tumor igenesis through superficial elevated type adenomas.