LOSS OF HETEROZYGOSITY OF CHROMOSOME 9P21 AND 7Q31 IS CORRELATED WITHHIGH-INCIDENCE OF RECURRENT TUMOR IN HEAD AND NECK SQUAMOUS-CELL CARCINOMA

To examine whether genetic factors influence the prognosis of cancer p atients, several polymorphic markers wc re used to determine the allel ic loss of certain areas of the genome. Two polymorphic markers, IFNA and D9S171 were used to study the loss of heterozygosity(LOH) of chrom osome 9p21 in 75 head and neck squamous cell carcinomas. LOH was detec ted in 14 out of 64(22%) DNA samples obtained from cancer specimens wh en at least one marker was used. The frequency of LOH was not correlat ed with the localization of the tumor, clinical stage of the patient, tumor size and lymph node involvement. However, the frequency of LOH w as significantly higher in the recurrent tumors than in the non-recurr ent tumors, suggesting that the allelic loss at 9p21 can be correlated with the short term prognosis of the patients. LOH was identified in only three out of 19(16%) samples when D7S522 was used as a marker. Ho wever, all of these three cases were recurrent, and two of the three s howed the allelic loss at 9p21 at the same time. These results indicat e that LOH of 9p21 and/or 7q31 is a novel prognostic factor independen t of other clinical factors for head and neck squamous cell carcinoma. Replication error (RER) was observed in 4 cancers, implicating geneti c instability in the carcinogenesis of a subset of head and neck squam ous cell carcinoma.