MOUTH CANCER AND THE HUMAN PAPILLOMA VIRUS
The human papilloma virus (HPV) is one of the most common virus groups in the world to affect the skin and mucosal areas of the body. Over eighty types of HPV have been identified. Different types of the human papillomavirus are known to infect different parts of the body. It infects the epithelial cells of skin and mucosa. The epithelial surfaces include all areas covered by skin and/or mucosa such as the mouth, throat, tongue, tonsils, vagina, penis, and anus. Infection with the virus occurs when these areas come into contact with a virus, allowing it to transfer between epithelial cells.
The most common forms of the virus produce warts (papilloma’s) on the hands, arms, legs, and other areas of the skin. The wart-like growths are called condyloma tissues. Condyloma tissue appears like a small, cauliflower-type growth on the skin. These growths are usually painless, but can cause some irritation, itching, or burning. It can be treated whenever it flares up, and is non malignant. Most HPV’s of this type are very common, harmless, non cancerous, and easily treatable. Genital warts are known technically as condylomata acuminatum and are generally associated with two HPV types, numbers 6 and 11 and can be sexually transmitted.
Cervical Cancer and Oral Cancer
There are other forms of HPV which are also sexually transmitted, and are a serious problem. These are; HPV-16, HPV-18, HPV-31, and HPV-45. These cancer-associated types of HPVs cause dysplastic tissue growths that usually appear flat and are nearly invisible. Dysplastic tissue is the presence of abnormal cells on the surface of the skin. Dysplasia is not cancer, but it is a tissue change seen prior to malignancy. A highly studied topic is HPV’s ability to cause cervical cancer. Dysplasia can be detected on the female cervix through a Pap smear test, or seen visually using a magnifying glass called a colposcope. The most dangerous HPV’s, 16 and 18, which are transmitted through sexual contact are known to cause up to 95% of cervical cancers. Now these two HPV’s are also being linked to oral cancer.
A study done by Dr. No-Hee Park showed that the mouth was, at the cellular level, structurally very similar to the vagina and cervix. Both organs have the same type of epithelial cells that are the target of HPV 16 and HPV 18. The majority of oral cancers are cancers of epithelial cells, primarily squamous cell carcinomas, not unlike the cancers that affect the cervix. Dr. Park’s study also showed that smoking and drinking alcohol help promote HPV invasion.. Combine tobacco and alcohol with HPV, and the epithelial cells in the mouth, and you may have the formula for the development of an oral cancer.
A recent study conducted by Dr. Maura Gillison at the Johns Hopkins Oncology Center furthered the premise that HPV is linked with certain types of oral cancer. In 25% of 253 patients diagnosed with head and neck cancers, the tissue taken from tumors was HPV positive and HPV 16 was present in 90% of these positive HPV tissues. This information helps to confirm that there is a strong link between HPV 16 and oral cancer. 25% of those diagnosed with oral cancer are non-smokers while the other 75% of those diagnosed have used tobacco in some form during their lifetimes. The research into the relationship of HPV and oral malignancies may give us clues as to the origin of cancer in those 25% of diagnosed individuals who did not smoke. Further research is being conducted into the relationship of HPV with oral cancers.
Treatments for Warts
Although there is currently no medical cure to eliminate a papillomavirus infection, the squamous intraepithelial lesions (SILs) and warts these viruses cause can be treated. Methods used to treat SILs include cold cautery (freezing that destroys tissue), laser treatment (surgery with a high-intensity light), LEEP (loop electrosurgical excision procedure, the removal of tissue using a hot wire loop), as well as conventional surgery. Similar treatments may be used for external genital warts. In addition, two powerful chemicals (podophyllin and trichloroacetic acid) are capable of destroying external genital warts when applied directly to them. Imiquimod cream has also been recently approved by the Food and Drug Administration (FDA) as an effective drug treatment. Imiquimod works by stimulating the immune system to fight the virus.
Scully C. Oral squamous cell carcinoma; from an hypothesis about a virus, to concern about possible sexual transmission.
Oral Oncol. 2002 Apr;38(3):227-34. Review.
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