Quantitative analysis of numerical chromosome aberrations in various morphological types of colorectal carcinomas

Quantitative analysis by fluorescence in situ hybridization (FISH) on thin paraffin-embedded tissue sections, using specific probes for chromosomes 11, 17, and 18 was employed in various morphological types of early and advanced colorectal cancer to clarify tumor cytogenetics. The chromosome index (CI) was calculated as a quantitative measure of the chromosome copy number. Compared with the CI of normal epithelium, the CI of chromosome 11 in villous components of adenomas or polypoid early cancers was decreased, while the CI in flat type or advanced colorectal cancers, conversely, was increased (P<0.05). The CI of chromosome 17 in villous components of adenomas and all cancers was higher than that of normal epithelium (P<0.05), but the differences were not significant. In protruding advanced cancers, the CI of chromosome 18 was significantly decreased (P<0.01) compared to the CI of normal epithelium. There was no significant chromosomal heterogeneity between the superficial and the deepest layer in each cancer. In mucosa adjacent to sessile and flat type cancers, the CI of chromosome 17 was significantly higher than the CI in normal epithelium or adenomas (P<0.05). These results suggest that numerical chromosome aberrations are associated with the histological type of adenoma and the morphological diversity of cancer in the colorectum, and that chromosome 17 abnormality occurs in mucosa adjacent to sessile and flat cancers.