BACKGROUND: Frequent loss of heterozygosity (LOH) has been reported inmany types of cancer, including head and neck carcinomas. Somatic deletions involving specific chromosomalregions are strongly associated with inactivation of the allele of a tumor suppressor gene located withinthe deleted region. In most studies concerning LOH in head and neck squamous cell carcinomas (HNSCC)the different anatomical sites are not distinguished. The behavior of tumors arising at various sitesdiffers significantly, however, suggesting different intrinsic tumor properties. In this study we comparedthe LOH on 22q and its relationship to clinicopathological parameters at the three major sites of HNSCC:oral cavity, larynx and pharynx. MATERIAL/METHODS: LOH and microsatellite instability (MSI) were studiedusing seven polymorphic microsatellite markers mapped to the 22q11-q13.3 region in 37 oral, 32 laryngeal,and 31 pharyngeal carcinomas. RESULTS: Two separate regions of LOH were identified in the laryngeal (22q11.2-12.1)and oral cavity (22q13.1-13.31) tumors. When the different anatomical sites were compared, a statisticallysignificant difference was found between the presence of LOH at D22S421 (p<0.001), D22S315 (p=0.014) and D22S929 (p=0.026) in the laryngeal tumors.
Conclusions: These data suggest that distinct regions on 22q are involved in LOH in oral cavity and laryngeal tumorigenesis, but do not support a similar association between the development of pharyngeal tumors and genes located on 22q. These findings implicate the presence of different tumor suppressor genes mapping to distinct regions on chromosome 22q in oral and laryngeal carcinomas.

Keywords: Alleles, Carcinoma, Chromosomes, Human, Pair 22, Gene Deletion, Laryngeal Neoplasms, Loss of Heterozygosity, Microsatellite Repeats, Models, Genetic, Pharyngeal Neoplasms, Research Support, Non-U.S. Gov