Interestingly, several studies have demonstrated that OSCC related to HPV infection shows a better outcome and a reduced risk of relapse and second tumors in comparison with HPV-negative tumors.28 A favorable prognosis for persons with HPV-16 DNA-positive OSCC was shown among 254 patients with HPV-associated cancers.29 There are a few possible reasons for this improved prognosis reported in the literature. First, the lack of “field cancerization” associated with HPV-positive cancers may be a factor leading to an improved prognosis. Additionally, the ability of HPV-positive cancer cells to induce apoptotic cell death in response to DNA damage also offers a possible explanation.30 The improved prognosis and treatment responses to chemotherapy and radiotherapy by HPV-positive tumors may suggest that HPV status must be determined to enhance treatment planning decisions and tailor therapy for each individual. In one study, patients with HPV-positive tumors responded better after induction chemotherapy (82% vs. 55%) and chemoradiation treatment (84% vs. 57%) in comparison with patients with HPV-negative tumors.31
Considering the importance of HPV found in the oral cavity, the detection of this virus and its subtypes has a strong clinical value. In February 2010, OralDNA Labs introduced the OraRisk HPV salivary diagnostic test. This is a noninvasive, user-friendly test that screens for the different types of HPV. It uses PCR to detect HPV DNA in a saliva sample. The laboratory report also will include useful information regarding the risk profile for each of the HPV types detected in the patient’s oral cavity. An evaluation of the feasibility of using oral-rinse sampling as a screening tool to monitor HPV status in patients with HNSCC, both before and after cancer treatment, showed that these samples permit detection of persistent oral HPV infection for as long as five years.32
Because of this probable link with HPV-associated HNSCC, the use of vaccination for the prevention of oral cancer has been suggested and is currently being researched. The arrival of HPV vaccination in women may lead to a decreased incidence of oropharyngeal cancer in the future. Vaccines designed strictly for prevention of cervical cancer and vulvar genital warts have been introduced within the past few years. The two commercially available vaccines are quadrivalent Gardasil, which protects against HPV types 6, 11, 16, and 18, and bivalent Cervarix, which targets HPV types 16 and 18. The impact of these vaccines on the incidence of persistent oral HPV infection remains undetermined. For these vaccines to be effective, they need to be administered before the patient becomes sexually active. Clinical trials evaluating the efficacy of the quadrivalent HPV vaccine in protecting against oral HPV infection are currently under way and remain an exciting possibility in the fight against oral cancer and HPV infection. The vaccines may also be useful in men: Immunogenicity studies have demonstrated that the vaccines induce a strong humoral immune response in males.33 This is a valuable finding because a considerable amount of HPV associated head and neck cancers occur in this population.