DNA index shift with disease progression in colorectal adenocarcinoma: a morphological and flow cytometric study.

DNA index (DI) values seen in 86 sporadic colorectal adenocarcinomas were related to clinical, morphological, and disease progression features. DI, whose overall distribution was bimodal with peaks in the diploid and from hypotriploid to tetraploid ranges, was related to pathological lymph node staging (pN), staging, lymphoid reaction, and tubular configuration. With increasing severity in pathological features, an irregular shift in DI class prevalence was seen, with no steady increase from diploidy to higher degrees of aneuploidy. All UICC stage I tumors (13% of total) were aneuploid, 50% being hypertriploid; diploidy (35%) and hypertriploidy (22%) prevailed in stage II carcinomas (41% of total), diploidy (35%) and hypotriploidy (30%) in stage III (30% of total), and triploidy (33%) in stage IV (15% of total). Amongst features related to stage (lymphoid reaction, depth of neoplastic embolization, grading, tubular configuration, and polymorphism), few were associated with DI, and none influenced DI shift and class prevalence through the stages. The biological capabilities of colorectal adenocarcinoma in relation to stage are expressed by certain aneuploid DI classes (hypertriploidy: absence of extracolonic spread; hypotriploidy: lymph node metastases; triploidy: distant metastases). Diploidy is unrelated to criteria defining stage above I and predicts 50% of cases with development of metachronous metastases. Irregular DI class shift through the stages may be attributable to different pathways of cancerogenesis and disease progression in diploid versus aneuploid carcinomas. Alternatively, assuming that the diploid fraction in aneuploid tumors contains neoplastic cells, pure diploid carcinomas represent the selection of a vital clone that may give rise to a further mixed population whose aneuploid DI is different and best fitted to express the biological capabilities of that given stage.