Loss of heterozygosity at 5q 21–22 (adenomatous polyposis coli gene region) in oral squamous cell carcinoma is common and correlated with advanced disease

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Abstract
We determined the frequency of loss of heterozygosity (LOH) at chromosome 5q21–22 (adenomatous polyposis gene region) in oral SCC from 49 patients using PCR‐based assays. Of 43 informative (heterozygous) tumors, 41.9% [95% confidence interval (CI)=27.0, 57.9] contained LOH at 5q21–22. LOH at 5q21–22 was strongly associated with stage at diagnosis: 100% (3/3), 50% (13/26), and 14% (2/14) of tumors from patients with distant metastases, regional spread, and localized disease, respectively, contained this genetic alteration (P=0.01). There were no statistically significant associations between LOH at 5q21–22 and other patient or tumor characteristics, but LOH was more commonly found in the tumors of heavy smokers, infrequent alcohol consumers, and in tumors containing either p53 mutations or HPV‐DNA. In univariate analyses, LOH at 5q21–22 was associated with poor prognosis (hazard ratio=1.8, 95% CI 0.8, 4.5); this relationship did not persist after adjustment for stage of disease (hazard ratio=1.1, 95% CI=0.4, 3.1). These data provide further evidence that inactivation of the APC gene and/or other genes at 5q21–22 is common and may be involved in the development and/or progression of oral SCC. Larger studies are needed to determine whether LOH at 5q21–22 is linked to known oral SCC etiologic factors and/or the prognosis of oral SCC patients, as well as to genetic instability at other loci involved in these malignancies