Background: Cytogenetics and molecular biology studies have indicated that a large subset of human colorectal adenocarcinomas have distal 1p chromosome arm deletions. The aim of this study was to evaluate the intratumor distribution of 1p deletions under the assumption that homogeneity is an indication of early occurrence.
Methods: Seventy-nine histologically selected primary sectors (40 superficial and 39 deep) and 3 lymph node metastases obtained from 20 human sporadic adenocarcinomas were analyzed. Interphase two-color fluorescence in situ hybridization (FISH) was applied to cytocentrifuged nuclei using a centromeric probe for chromosome 1 and a telomeric probe mapping to the 1p36 band.
Results: Deletions at 1p were observed in 35 of 82 tumor samples corresponding to 9 of 20 adenocarcinomas analyzed (45%). Seven of the 9 adenocarcinomas with 1p deletions showed an intratumor presence of these aberrations in all the different tumor sectors.
Conclusions: These data, acquired by FISH interphase cytogenetics, confirm that 1p deletions in colorectal adenocarcinoma are common and suggest that this structural chromosomal aberration occurs mainly as an early event in colorectal tumorigenesis.