Human papillomavirus in head and neck cancer: molecular biology and clinicopathological correlations.

Human papillomaviruses are known to cause cancers of the cervix and other anogenital tract sites. Epidemiologic and molecular pathology studies have also suggested that HPV infection may be associated with cancers of the head and neck. Modes of transmission of HPV infection in the head and neck region have not been fully resolved; however, perinatal transmission and an association between sexual behavior and risk for HPV-positive cancers have been presented. Among the HPV types infecting the mucosa, high-risk, intermediate-risk and low-risk genotypes are defined, depending on their presence in carcinoma or precursor lesions. The phylogenic groups of HPVs also showed a definite correlation with the morphology of head and neck tumors. The groups A6, A7, and A9 include viruses that are frequently demonstrated in basaloid and verrucosus squamous cell carcinomas known to associate with HPV infection. Integration of HPV DNA into the host cell genome occurs early in cancer development and is an important event in malignant transformation. There is a trend for patients with HPV-positive tumors to be nondrinkers or light drinkers, the majority of these patients are females, and the median age is lower than in the case of HPV-negative tumors, but this latter difference was not always statistically significant. In the Kaplan-Meier survival model, the HPV-positive verrucous and basaloid squamous cell carcinomas showed better survival rates than the HPV-negative typical squamous cell carcinomas. An increased radiocurability of HPV-positive head and neck squamous cell carcinoma (HNSCC) has also been demonstrated.