Loss of heterozygosity in the clonal evolution of flat colorectal neoplasms

摘要: In contrast to invasive colorectal carcinomas that develop in typical exophytic adenoma-carcinoma sequences, some cancers may evolve from flat mucosal dysplastic lesions. Despite their relatively small size, these lesions are often associated with high-grade dysplasia and show an aggressive clinical course. To delineate the genetic pathways clonal evolution of tumors, multiple foci were microdissected 13 cases allelic deletions 15 chromosomal arms analysed. Loss heterozygosity (LOH) was detected most frequently on 17p (77%), followed by 18q (69%), 5q (54%). five concomitant low-grade adenomas, only one case showed LOH adenoma foci. with/without submucosal invasion, early homogeneous several detected. Overall, thus (seven 10 LOH), 3p (two three (four seven LOH). addition LOH, patterns observed different portions dysplasias individual identified tumour progression, either linear or branching (divergent) trees. Positive immunostaining for p53 cases; these, all foci, four a majority and, retention 17p. Except configuration heterogeneity found be similar chaos late preinvasive stages adenoma. These findings suggest potentially course neoplasms.