Chromosome aberrations in adenomas of the colon. Proof of trisomy 7 in tumor cells by combined interphase cytogenetics and immunocytochemistry.

Thirty-five colon adenomas from 26 patients were analyzed with centromeric probes for chromosomes 1, 7, 17, X and Y in order to study numerical aberrations, chromosome imbalances, aneuploidy and tetraploidization. The fluorescent in situ hybridization (FISH) technique was applied to single-cell suspensions and a combination of FISH and immunocytochemistry (ICC) was employed to identify the cell type under study. Trisomy of chromosome 7 was detected in 37% of the cases. In 7 out of 13 cases this aberration was combined with abnormalities of one or 2 of the other investigated chromosomes. No correlation could be demonstrated between any of the detected chromosomal aberrations and size, localization or degree of epithelial dysplasia. With the combined FISH/ICC procedure, the abnormal cells were shown to be of epithelial rather than of stromal origin. Our data indicate that trisomy 7 is a common chromosome aberration in the epithelial component of colon adenomas.