Karyotypic progression in human tumors.
Karyotypic progression may be viewed in at least two ways. One approach seeks evidence for increasing and progressive deviation from the normal chromosome pattern in tumors. The clearest examples, found in some leukemias, are those in which successive karyotypic changes are superimposed on an already aberrant cell population. Evidence of chromosomal progression within solid tumors is far less frequent, possibly because the tumors themselves are at a relatively late stage in their evolution. An alternative approach, therefore, attempts to correlate the extent of karyotypic deviation with other aspects of tumor progression. Recent data, based on classical cytogenetic analyses and flow cytometry, are presented to determine relationships between karyotype and specific origin and morphology of tumors. The predominant theme which emerges, not surprisingly, is that the more deviant chromosome patterns are associated with other measures of increased biologic malignancy. What is surprising is the degree to which these properties are expressed in primary tumors and the relative lack of evidence for further karyotypic evolution with recurrence or metastasis. Examples of genetic instability, evolution through polyploidy, gene amplification, and selection for specific chromosomal rearrangement are found in populations of premalignant and malignant human cells. There is increasing recognition of the importance of tumor-specific chromosome aberrations in the stepwise progression from the normal to the fully neoplastic cell.