Throat Cancer and HPV Infection
Malignancies of the pharynx and larynx are collectively termed throat cancer. The majority of malignancies in this region are squamous cell carcinomas (SCC) . Although the incidence of tobacco and alcohol related oropharyngeal SCC are on the decline, the incidence of oropharyngeal SCC, particularly involving the tonsil, related to HPV in Western cultures is on the rise. HPV is identified in 45 to 95% of these tumors.
Recent studies have also identified prognostic differences in patients depending on the presence or absence of high-risk HPV. As a result, identifying high-risk HPV, most commonly p16, in tumors from the head and neck, and specifically the oropharynx, is quickly becoming a new standard of care. Studies have indicated that p16 is a useful surrogate marker for the presence of HPV in tumors; a suggested algorithm is to perform p16 immunohistochemistry (IHC), and if positive, then to proceed to PCR testing for confirmation. As a result, the application of this methodology to cytologic material, is likely to increase as well. A recent article in Diagnostic Cytopathology, Feb 2012, discusses the role of FNA of both primary and metastatic oropharyngeal SCC.
HPV positive tumors of the oropharynx are typically associated with a better prognosis, regardless of gender, age, lymph node status, stage, or treatment modality.
Although there is HPV identified in up to 25% of laryngeal carcinomas, the exact clinical significance is as yet undetermined, and additional studies are indicated.
The March 2012 issue of NewsPath®, published by the College of American Pathologists (CAP), provides a nice summary of the latest information on throat cancer and HPV infection, with a helpful list of references for your review.
“…In summary, HPV-related oropharyngeal SCC represents a distinct clinicopathologic subtype of head and neck SCC. HPV positivity in oropharyngeal SCC confers a better prognosis than HPV negativity, and HPV status is a robust prognostic indicator for overall survival, treatment response, and tumor control. HPV infection also occurs in laryngeal SCC, but the clinical relevance thereof requires further investigation.”