RESUMEN
BACKGROUND AND OBJECTIVES: It is important to identify potential biomarkers of tumorigenesis that can be utilized on histologically normal epithelia to determine the level of risk of tumor development. With the goal of possibly identifying a biomarker for the process of development of head and neck cancer, the amplification of int-2 was observed in patients with head and neck squamous cell carcinoma. MATERIALS AND METHODS: Fluorescence in situ hybridization using cosmid int-2 probe was performed on paraffin-embedded specimens from tumor and tumor-adjacent and tumor-distant epithelia of 20 patients. Buccal mucosa of cancer-free subjects who smoked and did not smoke cigarettes were used as control. Dot blot hybridization using digoxigenin-labeled int-2 probe was also performed on the frozen tissue from tumor and tumor-adjacent epithelia of 14 patients. RESULTS: In in situ hybridization, buccal epithelia of cancer-free subjects who smoked and did not smoke cigarettes, and tumor-distant epithelia of the patients with head and neck squamous cell carcinoma showed no int-2 amplification. However, eleven of tumor tissue (55%) and five of tumor-adjacent epithelia (25%) in 20 cases showed int-2 amplification. In dot blot hybridization, five tumor tissue (35.7%) and 2 tumor-adjacent epithelia (14.3%) in 14 cases, of which tumor tissue were all found to have int-2 amplification, showed int-2 amplification. CONCLUSION: The amplification of int-2 in the tumor tissue and the tumor-adjacent epithelia of the same cases supports the concept of field cancerization or clonal extension. Such genotype parameters may provide a genetic basis for the development of early recurrence or second primary tumors after therapeutic treatment of head and neck squamous cell carcinomas.