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.
