Chromosomal alterations in squamous cell carcinomas of the head and neck: window to the biology of disease.

Cytogenetic alterations underlie the development of squamous cell carcinomas of the head and neck (SCCHN). Because many of the molecular genetic changes in SCCHN result from chromosomal alterations, a complete perspective on the genetic changes in tumors requires a basic introduction to cytogenetics. This review presents a brief description of the latest cytogenetic techniques and a description of chromosomal alterations in SCCHN, their molecular correlates, and clinical implications. The most frequent cytogenetic alterations in SCCHN are gains of 3q, 8q, 9q, 20q, 7p, 11q13, and 5p and losses of 3p, 9p, 21q, 5q, 13q, 18q, and 8p. The karyotypes often provide an explanation for the mechanism by which the molecular genetic alterations arose. For example, the coordinate gains and losses involving whole arms of chromosomes 3, 5, 7, 8, and 9 often result from isochromosome formation. In addition, apparent allelic imbalances may not represent loss of heterozygosity but gene amplification. These results suggest that cytogenetic analysis is valuable for placing the molecular genetic findings in perspective at the cellular level. Cytogenetic endpoints may be useful tools for dissecting clinical differences in tumor behavior and response to therapy. Numerous studies are underway to examine the biology of and genetic alterations in SCCHN that will lead to additional markers for use as rapid, noninvasive screening methods for individuals at high risk for primary or recurrent SCCHN. Our goal is to minimize morbidity and mortality from SCCHN by identifying useful predictors of disease and recurrence risk and response to therapy to implement earlier detection and more effective prevention and/or treatment strategies.