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HPV and oral cancer: is there a link?

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Human papilloma virus and oral cancer-are they related? It is a question of rising concern, especially since there has been a noted increase of incidences of oral cancer since 1973 in patients who lack the traditionally accepted risk factors of tobacco use and alcohol consumption. (1)

Prevalence of Oral Cancer

The National Cancer Institute estimates the number of new cases of oral cancer in 2008 to be approximately 22,900, with 5,390 deaths. (2) The average five-year survival rate for oral cancer is 60 percent, even lower in patients of African-American descent. (3) The largest factor increasing a patient's chance of survival is early detection. Men are three times more likely to develop oral cancer than women. (4)

Risk Factors

One of the most pertinent risk factors for oral cancer has traditionally been tobacco use, closely followed by alcohol consumption. The carcinogens in tobacco have been shown to damage cell DNA, while alcohol, which contains ethanol, is known to inhibit the production of certain proteins, adding to the high risk of oral cancers. It is this pathway to oral cancer that still occupies the main focus of many prevention strategies today, such as tobacco cessation programs. But recent research has uncovered a distinct new pathway to the development of oral cancer, which is on the rise and may inform a more comprehensive approach: human papilloma virus (HPV) infection. (5)

For over 20 years, researchers have used retrospective case studies to investigate the possible link between high-risk HPV strains (HPV--HR) and oral squamous cell carcinoma (OSCC). One of the more recent comprehensive studies, published in the New England Journal of Medicine, shows that HPV-HR is present in the majority of these oral cancer lesions, and that the frequency of OSCC increases with high-risk sexual behaviors. (6) Separate studies analyzed more than 30 years of National Cancer Institute data on oral cancers. Researchers looked at about 46,000 cases, dividing them into oral cancers caused by HPV and oral cancers not connected to the virus. Their conclusion was that the incidence rates for HPV-related oral cancers rose steadily in men between 1973 and 2004, becoming about as common as those attributed to tobacco and alcohol. (7)

Both studies present mounting evidence that HPV is an etiologic agent for OSCC and that both men and women are at risk. Gillison remarks that the combined number of new cases of HPV-induced penile, anal and oral cancer in men is almost equal to the number of cervical cancers found in women each year. (8) In addition, husbands of women who have had cervical cancer are more likely to develop cancer in the upper respiratory and digestive tracts. (9) As the public awareness of HPV as a risk factor for oral cancer in men and women increases, oral health professionals will play a role in leading the health care sector in a new paradigm of oral cancer screening, patient education and prevention.

Current Research

Syrjanen et al. are credited with the first study to implicate HPV infection as a risk factor for some types of oral cancer, as early as 1983. (10) Since that time, researchers have been able to identify the most common HPV type leading to oral cancer as HPV-16, (6) one of the viral types known to cause cervical cancer and one of the targets of the new vaccine. Researchers have attempted to use what they know about HPV's role in cervical cancer to understand its role in oral cancer; for example, searching for overexpression of the cancer-causing E6 and E7 genes in HPV-positive oral cancer tumor specimens. One key study in the New England Journal of Medicine in 2007 showed that HPV-16 DNA was detected in 72 percent of tumor specimens and that 64 percent of the patients with cancer tested sero-positive for HPV-16 oncoprotein E6 and/or E7. (6)

While researchers are quick to point out that, unlike cervical cancer, HPV is not the cause of all head and neck cancers, but rather a subgroup of such cancers, the evidence is clear that HPV infection can lead to oral cancer even in the absence of other known risk factors, such as alcohol and tobacco use. (5)

Studies have also indicated that HPV-induced oral cancer lesions have unique properties of histology, location and survival rate. HPV attacks basal cells of the epithelium. Histological studies of HPV-induced oral cancer lesions show that the tumors are more basaloid in nature than other oral cancer lesions. (11) Furthermore, HPV-induced lesions are more often found in the oropharynx, tonsils and at the base of the tongue. (12) Some word of hope for patients diagnosed with HPV-induced oral cancer is that this subgroup of oral cancer shows a higher survival rate by 28 percent than other types of oral cancer, a lower rate of recurrence and a better response to treatment. (13)

The body of research on HPV and oral cancer over the past 20 years is extensive, but additional research is still needed to identify HPV's specific role in the development of oral cancer and to determine how the public and oral cancer patients can benefit from this new knowledge.

A Call to Action in the Dental Community

According to the Journal of Dental Education, less than 20 percent of the U.S. population receive an oral cancer examination and moreover, Black and Hispanic patients were less likely to have this type of screening, plausibly due to lack of access to dental care. (14) There are a variety of oral cancer screening methods. A two-minute comprehensive oral exam is the most common method used to detect visible lesions. (15) This type of exam includes visual inspection and palpation of high-risk areas, such as the floor of the mouth, lateral borders of the tongue and soft palate. Other screening and diagnostic methods include the use of chemiluminescent light, mucosal staining with blue dye called toluidine blue, brush biopsy, incisional biopsy and punch tissue biopsy. (16)

As informative and responsible clinicians, dental hygienists who detect a suspicious leukoplakia and erythroplastic lesion need to inform their dental colleagues so that appropriate referral and further testing are pursued. As educators, clinicians and community health advocates, dental hygienists have the power to change these concerning statistics. They can provide their patients with informational packets on oral cancer and HPV, the new risk factor. They can empower their patients to take a proactive role in their health and teach them how to perform a one-minute weekly oral self-examination. (17)

Along with demonstrating a self-assessment procedure to the patient, the dental hygienist needs to offer visual criteria for determining significant deviations from normal. (18) The National Cancer Institute is an excellent resource to contact for free publications on oral cancer screenings and other patient education materials. At the dental office, developing a simple but comprehensive "educate, detect and diagnose" protocol could aid the dental team with time management and efficient care.

An inspiring educator once advised, "Develop a passion for learning. If you do, you will never cease to grow." (19) One of the best ways dental hygienists can positively impact the community is by staying current with new research developments. Organizations such as the American Cancer Society, the National Cancer Institute and the Oral Cancer Foundation offer updated clinician and patient information on topics such as oral cancer treatment, the link to HPV and vaccination development.

References

(1.) Chaturvedi AK, Engels EA, Anderson WF, Gillison ML. Incidence trends for human papillomavirus-related and -unrelated oral squamous cell carcinomas in the United States. J Clin Oncol 2008; 26(4): 612-9.

(2.) Oral cancer. National Cancer Institute, 2008. Available at www.cancer.gov/cancertopics/types/oral/. Accessed Sep. 2008.

(3.) Oral cancer five-year survival rates by race, gender and stage of diagnosis. National Institute of Dental and Craniofacial Research, 2004. Available at www.nidcr.nih.gov/DataStatistics/FindDataByTopic/ OralCancer/OralCancer5YearSurvivalRates.htm. Accessed Sep. 2008.

(4.) "Oral cancer incidence (new cases) by age, race and gender." National Institute of Dental and Craniofacial Research, 2004. Available at www.nidcr.nih.gov/DataStatistics/FindDataByTopic/OralCancer/ OralCancer5YearSurvivaIRates.htm. Accessed Sep. 2008.

(5.) Applebaum KM, Furniss CS, Zeka A, et al. Lack of association of alcohol and tobacco with hpv 16-associated head and neck cancer. J Natl Cancer Inst 2007; 99(23):

(6.) D'Souza G, Kreimer AR, Viscidi R, et al. Case-control study of human papillomavirus and oropharyngeal cancer. N Eng J Meal 2007; 356(19): 1944-56,

(7.) Schwartz SM, Daling JR, Doody DR, et al. Oral cancer risk in relation to sexual history and evidence of human papillomavirus infection. J Natl Cancer Inst 1998; 90(21): 1626-36.

(8.) Gillison ML. John Hopkins Audio Release, 2007. Available at www.oralcancerfoundation.org/hpv/index.htm. Accessed Sep. 2008.

(9.) Ragin CCR, Modungo F, Gollin SM. The epidemiology and risk factors of head and neck cancer: a focus on human papillomavirus." J Dent Res 2007; 86(2): 104-14.

(10.) Syrjanen K, Syrjanen S, Lamberg Met al. Morphological and immunohistochemical evidence suggesting human papillomavirus (HPV) involvement in oral squamous cell carcinogenesis. Int J Oral Surg 1983;12(6): 418-24.

(11.) Chustecka Z. Oropharyngeal cancer linked to human papillomavirus. Medscape Medical News, May 9, 2007 (review). Available at www.medscape.com/viewarticle/556285. Accessed May 2007.

(12.) Kreimer AR, Clifford GM, Boyle P, Franceschi S. Human papillomavirus types in head and neck squamous cell carcinomas worldwide: a systematic review. Cancer Epidemiol Biomarkers Prey 2005; 14(2): 467-75.

(13.) Ragin CC, Taioli E. Survival of squamous cell carcinoma of the head and neck in relation to human papillomavirus infection: review and metaanalysis. Int J Cancer 2007; 121(8): 1813-20.

(14.) Kerr AR, Changrani JG, Gany FM et al. An academic dental center grapples with oral cancer disparities: current collaboration and future opportunities. J Dent Educ 2004; 68(5): 531-41.

(15.) National Cancer Institute. Oral cancer screening (PDQ[R]). Available at www.cancer.gov/cancertopics/pdq/screening/oral/healthprofessional/ allpages.

(16.) Getting screened for oral cancer. Oncolog 2004; 49(4) Online version available at http://www2.mdanderson.org/depts/oncolog/articles/04/4-apr/ 4-04-hc.html.

(17.) Want some life-saving advice? ask your dental hygienist about oral cancer. Available at www.adha.org/downloads/oralcancer.pdf.

(18.) Darby ML. Mosby's comprehensive review of dental hygiene, 6th ed. St Louis: Mosby, 2006; p. 691.

(19.) D'Angelo AJ. Quoted online at www.quoteworld.org/quotes/3350.

Originally from Israel, Reut Douer is a senior dental hygiene student at the University of Southern California. She holds a bachelor's degree in world history from the University of California Santa Cruz. She hopes to someday travel around the world to provide dental hygiene services in areas where access is limited.

Dawn Jarocki, RDH, BS, graduated from the dental hygiene program at the University of Southern California's School of Dentistry, where she was honored to receive the Patient Education Award in 2008. She is currently working in private practice striving to educate her patients about oral cancer and the importance of regular screenings. She hopes to return to teaching part-time sometime in the future.

Carlos Sanchez, RDH, BS, is a native Southern Californian and a recent graduate of the University of Southern California School of Dentistry Dental Hygiene Program. He is currently pursuing his master's in public health at USC with a focus on the oral health care needs of primarily underrepresented children and the appropriate access to care for this population.
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Title Annotation:strive: the student view
Author:Douer, Reut; Jarocki, Dawn; Sanchez, Carlos
Publication:Access
Geographic Code:1USA
Date:Sep 1, 2008
Words:1892
Previous Article:Correction.
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