Genetic instability and the development of recurrence of primary tumor and second primary tumor during head and neck tumorigenesis.

To determine whether the degree of genetic instability is associated with the development of recurrence of primary tumor (RPT) and second primary tumor (SPT), we examined 46 cases of head and neck squamous cell carcinomas (HNSCC) by nonisotopic in situ hybridization using chromosome specific DNA probes for chromosome 9 and 17. Forty-six cases were classified into three groups; group I, 15 cases without developing RPT and SPT; group II, 21 cases with RPT, and group III, 10 cases with SPT. We demonstrated the statistical significant increment of genetic instability in terms of normalized chromosome index (NCI) and polysomy index (PI) of chromosome 9 and 17 from normal adjacent to malignant lesions (ANL), to hyperplasia (HYP), to dysplasia (DYP), to squamous cell carcinomas (SCC). Our results demonstrated the trend of increased chromosome indices as the tissue progressed from ANL to SCC in group II over group I. However, when we compared the genetic instability between group I and the specimens from the patients who developed RPT within 6 months (group III), we found the significant increment of PI of both chromosome 9 (0.84 +/- 0.54 vs 1.25 +/- 0.46, p = 0.10) and 17 (1.02 +/- 0.62 vs 1.89 +/- 0.87, p = 0.06) on ANL in the later group. Our results also demonstrated the higher trend of genetic instability on ANL in group III over group I as shown by the statistical significance of NCI of both chromosome 9 (0.98 +/- 0.12 vs 1.06 +/- 0.02, p = 0.05) and 17 (1.02 +/- 0.09 vs 1.10 +/- 0.05, p = 0.05). These results suggested that the degree of genetic instability might be used as a potential molecular marker for the risk assessment of early RPT and SPT development during head and neck tumorigenesis.