CYTOGENETIC ANALYSIS OF COLORECTAL ADENOMAS - KARYOTYPIC COMPARISONS OF SYNCHRONOUS TUMORS

The phenotypic progression of colorectal tumors is driven by their ste p-by-step acquisition of genomic alterations. These pathogenetically i mportant mutations are at the same time markers of tumor clonality. Th e aim of this study was to describe the clonal relation among synchron ous colorectal adenomas. Twenty-four colorectal adenomas from 11 patie nts were subjected to chromosome banding analysis. Clonal chromosome a bnormalities were found in 20 tumors. Recurrent structural rearrangeme nts involved chromosomes 1, 13, 17, and 18. The most common numerical changes were gain of chromosomes 7, 13, 20, and 3 and loss of chromoso me 18. Eight adenomas had subclones as evidence of clonal evolution. S imilar clones in separate polyps were seen in tumors from 6 patients; these adenomas were always located in the same part of the large bowel . In 2 patients, both with one rectal adenoma and one adenoma in the c olon, no karyotypic similarity between the lesions was found. Our find ings indicate that whereas close, but macroscopically distinct, synchr onous colorectal adenomas usually have a common pathway of progression , perhaps even the same clonal origin, large bowel adenomas at a consi derable distance from one another exhibit karyotypic differences, indi cating that they arise independently. (C) Elsevier Science Inc,, 1998.