Most cancer cells have acquired clonal chromosome abnormalities. An increasing number of characteristic aberrations, in particular balanced changes, are with remarkable specificity associated with distinctive morphological and clinical disease characteristics. The identification of these recurrent aberrations has several important implications. First, cytogenetics has become an increasingly important tool in the clinical management of cancer patients to help establish a correct diagnosis, to predict prognosis and to select the most appropriate treatment. Second, the cytogenetic information has provided invaluable help to identify genes of importance in the carcinogenic process by focusing the attention to chromosomal sites that may harbour genes which when rearranged lead to neoplasia. Practically, all balanced structural rearrangements that have been characterised at the molecular level have been found to exert their action through one of the two alternative mechanisms: deregulation, usually overexpression, of a seemingly normal gene in one of the breakpoints, or the creation of an abnormal hybrid gene through fusion of parts of two genes, one in each breakpoint.
Key Concepts
Chromosome aberrations are a characteristic feature of neoplasia.
Chromosome abnormalities have been reported in almost 70 000 human neoplasms.
Recurrent balanced chromosome rearrangements, in particular translocations, are associated with distinctive tumour characteristics.
Cancer‐associated chromosome changes are of clinical importance for diagnosis, prognosis and treatment.
The breakpoints of balanced structural chromosome aberrations point at the locations of cancer‐relevant genes.
Cancer‐associated structural chromosome abnormalities lead to the formation of hybrid genes through fusions of parts of two genes located in the breakpoints.
Almost 800 gene fusions created by an acquired chromosome change are known.
