Archive for July, 2012
HPV 411: The scoop on Human Papillomavirus
HPV (human papillomavirus) is a big topic nowadays. Patients are asking about it because it has been addressed as a topic in popular media (The HBO series ‘Girls’), because of commercials for the HPV vaccines (Gardasil and Cervarix), and because the have heard about it in the context of an abnormal Pap smears. There’s a lot of misinformation out there (particularly in the media) and I’d like to combat it with some facts.
First, let’s review what the virus is and what it does. HPV is not just one virus. It’s a family of viruses, of which over 30 different types (identified by numbers such as ‘Type 16’) infect the anogenital area and can be transmitted by sexual activity.
**Barrier contraception (such as condoms or dental dams) can prevent most HPV transmission between partners.**
Some types of HPV cause genital warts. These types are typically described as ‘low-risk’ for subsequent development of precancerous or cancerous lesions. Genital warts are visible on the skin and mucous membranes. They are often noticed by patients on self-examination. They can also be diagnosed by a doctor at the time of an annual visit during a visual inspection of the genital area.
Some HPV types are described as ‘high-risk’ for the development of precancerous or cancerous lesions. That’s these types of HPV infection are the cause of nearly all cases of cervical cancer and may be linked to rarer cancers of the vulva (female external genitalia), vagina, anus, penis, and oral region. Most infections with even these ‘high-risk’ types resolve spontaneously (i.e. without treatment) and do not cause disease.
HPV screening in women is done indirectly through the use of Pap smears or Pap tests. A Pap smear is a microscopic evaluation of cells obtained by swabbing the cervix. These cells are examined for the types of cellular changes typical of HPV infection. A Pap smear is often performed by a doctor or other health care provider at the time of a woman’s routine annual visit. An abnormal Pap test requires further evaluation, usually with colposcopy (see below).
HPV testing can be performed directly by a laboratory. A sampling of cervical cells (obtained by a healthcare provider at the time of a Pap smear) is sent to a lab to detect the presence of DNA from the HPV virus. This test is usually reserved for women over 30 or those who have already had an abnormal pap smear. HPV testing is not routinely performed on men, nor is it routinely performed in the anal or oral region. That’s because cancers of these other organs are rare in comparison to cervical cancer.
Most HPV infections in young women are self-limited (i.e. they resolve on their own and without treatment) and have no long-term health consequences. Up to seventy percent of HPV infections resolve in 1 year and ninety percent may resolve in 2 years. However, when the infection persists — in 5% to 10% of infected women — there is a significant risk of developing precancerous lesions of the cervix. Over 10-15 years, these lesions can progress to invasive cervical cancer. The long interval between precancerous lesions and their development into cancer allows ample opportunity for detection and treatment of the pre-cancerous lesion. Progression to invasive cancer can be almost always prevented when regular screening detects precancerous lesions and treatment is provided in a timely fasion.
A colposcopy (from the Greek kolpos “hollow, womb, vagina” + skopos “look at”) is done to evaluate the cervix after an abnormal Pap result. The colposcope itself is just a microscope with a light allowing a doctor to examine an illuminated, magnified view of the cervix, vagina and vulva. Many premalignant and malignant lesions have specific characteristics which make them look ‘suspicious’ when examined in this fashion. These areas can then be targeted for biopsy (taking a piece of tissue to be evaluated by a Pathologist). The main goal of colposcopy is to prevent cervical cancer by detecting precancerous lesions early so that they can be treated before they become malignant.
Treatment of precancerous or premalignant lesiosn usually involves minor surgical procedures (a LEEP or a cone biopsy) in which uses a cauterizing loop or other small cutting instrument to remove the affected part of the cervix. Patients are usually advised to avoid sexual intercourse for at least 6 weeks to allow complete healing. Cryotherapy (freezing the affected portion of the cervix with liquid nitrogen) is also used in some areas where the aforementioned procedures are not feasible (i.e. in the developing world). Cryotherapy is not usually used for premalignant lesions because it is less likely to remove the entire lesion and because there is no way to reliably identify the extent of tissue destroyed. Therefore, it is considered a less effective therapy and is used only for lesions which are not precancerous or in situations in which a LEEP, LETZ or cone biopsy cannot safely be performed.
There is some increased risk of reduction or loss of fertility and an increased risk of certain pregnancy complications (including preterm birth) with some of these procedures, especially if they need to be repeated several times. A doctor who performs these types of procedures can go into greater detail about the risks of a specific procedure he or she recommends.
**In summary: HPV can cause cervical cancer. The best defense against cervical cancer is to get reguar screening with Pap smears and HPV tests as recommended by your healthcare provider. An abnormal screening test deserves prompt follow-up and may require colposcopy. Medical procedures (LEEP, cone biopsy) which are performed on individuals with HPV infection at the time they are diagnosed with precancerous lesions are effecive at preventing cervical cancer. These procedures may carry a risk of pregnancy-related complications and should be discussed with your healthcare provdier. Condom use and HPV vaccination may prevent some HPV infections.**
I’ll be blogging about HPV vaccination next.
The Gynecologist 