Epithelial neoplasm of the colorectum: correlation of histopathological features with cytogenetic studies

Seven cases of primary rectosigmoid epithelial neoplasm, including a tubular adenoma, a villous adenoma with malignant change and five adenocarcinomas, were cytogenetically studied with short-term cultivation and GTG-banding. The tubular adenoma showed karyotypic normality. The other six malignant tumors were hyperdiploid in chromosomal modal number and showed multiple aberrations. The complexity of chromosomal aberrations increased proportionally to the pathologic stage. No common chromosome change to all of the tumors was found. The most common recurrent chromosome changes were extra gains of chromosomes #7 and #8q, which were found respectively in four of the six malignant tumors. Two recurrent structurally abnormal chromosomes were i(8q) and der(10)t(10;?)(p15;?). No case showed sex chromosome change, except one tumor from a male patient who obtained an extra X chromosome. All these chromosome changes found were consistent with the results reported by other investigators. Deletions of #5q and #17 were nevertheless only found in one and two of our six malignant cases, respectively. No cases showed a deletion of #18q. The possible molecular mechanisms of these recurrent chromosome aberrations were also discussed.