Chromosomes, genes, and cancer

Abstract

The 'modern' era of tumor cytogenetics began in the 1950s and accelerated rapidly with the development of so-called banding techniques in the 1970s. During this period, chromosome studies of neoplasms added significantly to our understanding of various aspects of tumor biology. The recognition that most neoplasms have visible cytogenetic alterations contributed to general acceptance of the view that somatic genetic changes are important in tumorigenesis. In addition, the demonstration that in a given tumor all the neoplastic cells often have the same karyotypic change, or related changes, helped to indicate the derivation of most tumors from a single altered cell. Presumably, the specific somatic genetic change, often recognizable at the chromosome level, confers on the progenitor cell a selective growth advantage, allowing its progeny to expand as a neoplastic 'clone' of unicellular origin. Most current developments in tumor cytogenetics, however, have related to another aspect that has been increasingly recognized as techniques have improved: specific alterations in particular chromosomes are associated, with different degrees of consistency, with specific types of tumors, or with neoplasia in general. It has been suggested that these nonrandom karyotypic changes might indicate sites in the genome where particular genes important in carcinogenesis are located, and provide clues as to how the function of such 'oncogenes' might be significantly altered. This brief review of recent findings focusses on this aspect of the cytogenetics and related molecular genetics of neoplasia, with emphasis primarily on our own recent studies in leukemia and lymphoma.