Polysomies of chromosomes 7 and 17 in head and neck squamous cell carcinomas.

Abstract

To determine the polysomies (ie, cells with > or = 3 chromosome copies) of chromosomes 7 and 17 in tumor tissue, histologically normal epithelia adjacent to the tumor (tumor-adjacent epithelia), and buccal epithelia distant from the tumor (tumor-distant epithelia) of head and neck squamous cell carcinomas. Nonfluorescent, nonisotopic, in situ hybridization using chromosome-specific centromeric DNA probes for chromosomes 7 and 17 was performed on the formalin-fixed, paraffin-embedded specimens from tumor and tumor-adjacent and tumor-distant epithelia of 19 patients with head and neck squamous cell carcinomas and from buccal epithelia of cancer-free control subjects who smoked and did not smoke cigarettes. Four hundred nuclei in tumor tissue and 200 nuclei in histologically normal epithelia were scored for hybridized signals in each sample. Buccal epithelia of cancer-free control subjects who smoked and did not smoke cigarettes showed no difference in the polysomies of chromosomes 7 and 17, respectively. The polysomies of chromosomes 7 and 17 in the tumor cells were higher than those in the tumor-adjacent epithelia (P < .001 for both), tumor-distant epithelia (P < .001 for both), and buccal epithelia of cancer-free control subjects who smoked and did not smoke cigarettes (P < .001 for both). The polysomies of chromosomes 7 and 17 in the tumor-adjacent epithelia were higher than those in the tumor-distant epithelia (P < .001 for both) and the control buccal epithelia (P = .002 and P < .001, respectively). The tumor-distant epithelia and the control buccal epithelia for the polysomies of chromosomes 7 and 17 had no differences. The finding of genotypic abnormalities in the tumor-adjacent epithelia supports the concept of field cancerization. Such genotypic parameters may provide a genetic basis for the development of an early recurrence or second primary tumors after therapeutic treatment of head and neck squamous cell carcinomas.