[Detection of chromosomal numerical aberration in early colorectal carcinomas using fluorescence in situ hybridization].

The authors have performed fluorescence in situ hybridization (FISH) in tissue sections of archival paraffin-embedded blocks of seven cases in adenoma and ten cases in carcinoma in order to clarify which chromosomal aberration occurred in association with multi-step carcinogenesis in colorectal carcinomas, using alpha-satellite DNA probes to chromosome 11 and 17, D11Z1 and D17Z1, respectively. Monosomy of chromosome 11 was most frequented (5/7, 71.4%) in adenoma, and trisomy of chromosome 17 was predominant (9/10, 90.0%) in carcinoma. The numerical chromosomal aberrations can be already detected at the stage of adenoma, and monosomy of chromosome 11 was mainly observed in adenoma. Furthermore, malignant transformation arising from adenoma accounted for most of the trisomic change in chromosome 17. Consequently, applying the FISH technique to tissue sections from archival paraffin embedded specimen, it would be possible to distinguish between the cancerous and non-cancerous regions in view of chromosomal numerical aberrations. The authors emphasized that intratumoral heterogeneity could be elucidated at the chromosomal level.