Loss of heterozygosity at 5q21-22 (adenomatous polyposis coli gene region) in oral squamous cell carcinoma is common and correlated with advanced disease

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.