Characterization of Translocations in Human Cancer

Recurring chromosomal abnormalities are associated with distinct subtypes of leukemia or lymphoma that have unique morphologic, immunophenotypic, and clinical features, such as response to therapy (1 –4 ). Thus, cytogenetic analysis of an individual’s malignant cells plays a major role in the diagnosis and subclassification of a hematologic neoplasm. Examples of the clinical-cytogenetic subtypes of acute myeloid leukemia (AML) include the t(15;17) in acute promyelocytic leukemia (AML-M3), and the t(8;21) in acute myeloblastic leukemia with maturation (AML-M2) (1 –3 ). A number of recurring abnormalities have also been recognized in solid tumors. At present, there are more than 600 recurring translocations associated with human cancers (1 –3 ,5 ). The vast majority of these have been identified in the hematologic malignant diseases; however, some are associated with mesenchymal tumors, particularly the pediatric small round blue cell tumors, e.g., Ewing sarcoma and rhabdomyosarcoma. Although epithelial tumors represent the most common cancers (lung, breast, and colon carcinomas), only a few recurring abnormalities have been identified in these diseases.The Mitelman Database of Chromosome Aberrations in Cancer provides a registry of the abnormal karyotypes identified in greater than 37,000 neoplasms (>100,000 aberrations) (5 ). Another relevant database has been developed by the Cancer Chromosome Aberration Project, which integrates cytogenetic and genomic databases relevant to cancer (http://www.ncbi.nlm.nih.gov/CCAP ).