Human Papilloma Virus (HPV) and Anal Dysplasia
-Connie Pennington, MD
Human Papilloma Virus or HPV is a group of more than 40 virus types. HPV is the most common sexually transmitted disease, and many carriers are asymptomatic, or simply unaware of their infection. Some types of HPV cause genital warts and a small number may lead to cervical, vulva, vaginal, penile, and anal cancer. They also can be transmitted to the mouth and throat, and are even implemented in an increased risk for cardiovascular disease.
Screening for HPV is done by a PAP smear of the cervix and anal canal. When abnormal cells are detected, biopsies are performed. The cervix is treated by a cauterizing loop, or cryotherapy. The anal canal is treated by biopsy mapping, resection of affected skin and or mucosa, and careful surveillance. Currently there is no cure for HPV, and the goal is detection and eradication of the abnormal cells that are caused by HPV.
Recommendations for screening are based on the following risk factors:
History of genital warts
All women with a history of cervical or vulvar cancer or pre-cancerous lesions, such as a positive PAP smear
Partner with cervical cancer or precancerous lesions, such as a positive PAP smear
All HIV positive men and women
History of anal intercourse
Transplant recipients or people taking life long immunosuppressive drugs
There are two vaccines available for HPV, Cervarix by GlaxoSmithKline and Gardasil by Merck. These vaccines target HPV types 16 and 18, which are thought to be responsible for up to 70% of cervical cancer. It is unknown if these vaccines prevent condyloma or cancer.
All anal warts should be removed and examined by a pathologist. The majority of anal warts do not display abnormal cell growth, but a few do and this is called dysplasia. When anal dysplasia is detected it is further classified by a following criteria:
Anal Intraepithelial Neoplasia (AIN) I: Low grade dysplasia
Anal Intraepithelial Neoplasia (AIN) II: Moderate grade dysplasia
Anal Intraepithelial Neoplasia (AIN) III: High grade dysplasia
High grade dysplasia is a precursor to anal cancer, but it is not anal cancer. Treatment consists of careful observation and frequent biopsies to assess progression of disease. Women also need routine cervical PAP smears, as the presence of Anal Intraepithelial Neoplasia puts a female at risk for having Cervical Intraepithelial Neoplasia.
Risk factors for the development of anal dysplasia include HPV infection (most common), history of anal intercourse, positive HIV test, cigarette smoking, and people with a weakened immune system (solid organ transplantation).
The risk of anal dysplasia progressing into anal canal cancer is less than 5%, although its progression may be significantly higher in HIV positive individuals.
The most important factor in dealing with anal dysplasia is close follow up. This may mean a careful anal examination every 3-6 months. Anal PAP smears and anal canal biopsies may be utilized. Generally biopsies can be performed in the office with local anesthesia.The importance of close follow-up cannot be over emphasized. If any new warts or anal lesions develop be sure to alert your health care provider immediately.