p53 mutations in head and neck cancer: new data and evaluation of mutational spectra

It has been suggested that the frequency, type, and location of p53 mutations (mutational spectra) can be linked to specific exogenous and endogenous carcinogenic agents and processes. Squamous cell carcinoma of the head and neck (SCCHN) provides an excellent tumor model to evaluate the utility of the p53 mutational spectra, given that it has well-defined and strong risk factors (tobacco and alcohol). The purpose of this analysis was to establish the pattern of p53 mutations in SCCHN and evaluate this mutational spectrum in comparison to the spectra for other cancers with similar and different risk factors, including cancers of the esophagus, lung, and colon. p53 mutational data were obtained from head and neck tumors collected at the University of North Carolina Hospitals and the published literature. A total of 14 of 33 tumors from the University of North Carolina Hospitals (42%) were found to have a p53 mutation. The alterations included three transversions, seven transitions, two deletions, and two suspected codon 47 polymorphisms. In general, SCCHN and esophageal cancer share a similar mutational pattern in contrast to colon cancer. These two aerodigestive tract cancers were statistically different from lung cancer, despite sharing tobacco as a major risk factor. For example, G-->T transversions, a mutation type considered to be characteristic of exogenous DNA-damaging agents including tobacco smoke carcinogens, varied among tobacco-related cancer sites (14% SCCHN, 11% esophageal, and 31% lung) in contrast to colon cancer (6%). The comparison of mutational spectra for SCCHN and other cancers indicates that the effects of both tobacco and alcohol exposure may yield a pattern of p53 mutations that reflects elements of both exogenous and endogenous exposures.