Genital Warts
A Primer on HPV
Human papillomavirus (HPV) is now recognized as the major cause of cervical cancer, a disease that
kills more than 200,000 women around the world each year. HPV is very common, however, and of the
more than 100 types of HPV, fewer than 20 are considered “high-risk” for the development of cancer.
The following is a brief guide to HPV, including transmission, incidence, treatment, and its connection
to genital warts and cancer.
The Signs of HPV
Certain types of HPV may cause warts, or papillomas, which are benign (noncancerous) tumors.
All warts are caused by papillomaviruses, but each type of HPV grows only on specific areas of the
body. The HPV types that cause the common warts that grow on hands and feet are not transmitted
sexually and differ from those that cause growths in the mouth and genital area.
About 40 types of HPV can be sexually transmitted and infect the genital area, including the
cervix, vagina, vulva, anus and penis. HPV is, in fact, one of the most common sexually transmitted
diseases, with many millions of new genital HPV infections occurring each year in the United States.
As HPV rarely causes symptoms and therefore the majority of infections are unnoticed, genital HPV
infections are likely to be even more common than we think.
Most genital warts are caused by HPV types 6 and 11. Warts may appear within several weeks or
months after sexual contact with a person who has HPV, or they may never appear. HPVs may also cause
flat, abnormal growths in the genital area and on the cervix. Again, HPV infections often do not
cause any symptoms.
HPV Types and Their Association with Cancer
Research has clearly shown that HPVs are the major cause of cervical cancer. Studies also
suggest that HPVs may cause a fraction of the cancers of the anus, vulva, vagina, and penis, and
some cancers of the oropharynx (the middle part of the throat that includes the soft palate, the
base of the tongue, and the tonsils).
Some types of HPVs are referred to as "low-risk" viruses because they rarely develop into cancer;
these include HPV-6 and HPV-11, although the most common low-risk types cause neither warts nor
cancer. HPVs that can lead to the development of cancer are referred to as "high-risk." Both
high-risk and low-risk types of HPVs can cause the growth of abnormal cells, but usually only the
high-risk types may lead to cancer. Sexually transmitted, high-risk HPVs have been linked with
anogenital cancer in both men and women, and include HPV types 16, 18, 31, 33, 39, 45, 51, 52, 56,
58, 59, 68 and 69. These high-risk types of HPVs cause growths that are usually flat, as compared
with the warts caused by HPV-6 and HPV-11.
Risk Factors for HPV and Cervical Cancer
Women who have many sexual partners have a higher chance of developing an HPV infection in the
cervix. Infection with high-risk HPV types, specifically, increases the odds that a woman will
develop cervical cancer. However, while HPV infections are very common, cervical cancer is not.
The vast majority of HPV infections go away without treatment and do not cause cervical cancer.
Studies suggest that development of cervical cancer depends on a variety of factors acting on women
with high-risk HPVs. These cofactors include: smoking, having many children, long-term oral
contraceptive use, and HIV infection. Effective screening and treatment of precancerous cervical
conditions is highly effective in the prevention of cervical cancer in HPV-infected women.
Precancerous Cervical Conditions
Abnormal cervical cells can be detected when a Pap test is done during a gynecologic exam.
Various terms have been used to describe the abnormal cells that may be seen in Pap tests. The
Bethesda System (the major system used to report the results of Pap tests) divides the most common
clearly abnormal Pap test results into low-grade squamous intraepithelial lesions (LSILs), high-grade
squamous intraepithelial lesions (HSILs), and cancer. Squamous cells are thin, flat cells that cover
internal (e.g. cervix) and external (e.g. skin) surfaces of the body. LSILs are mild cell changes due
to HPV infections, which are common, especially in young women. The majority of LSILs return to
normal over months to a few years but, if HPV persists, HSIL can develop. HSILs are not cancer, but
they may eventually lead to cancer and should be treated by a doctor.
Screening and Follow-up for Cervical Conditions
Screening for cervical cancer consists of regular Pap tests for women who have been
sexually active for approximately three years or who have reached 21 years of age.
Women 65 to 70 years of age who have had at least three normal Pap tests and no abnormal Pap
tests in the last 10 years may decide, upon consultation with their healthcare provider, to
stop cervical cancer screening. Women who have had a total hysterectomy (removal of the uterus
and cervix) do not need to undergo cervical cancer screening, unless the surgery was done as a
treatment for cervical precancer or cancer.
According to the new 2001 Consensus Guidelines for Managing Women
with Cytological Abnormalities, if either HSIL or LSIL is found
on a Pap test, colposcopy and biopsy of any abnormal areas are recommended.
Colposcopy is a procedure in which a lighted magnifying instrument
called a colposcope is used to examine the vagina and cervix. Biopsy
is the removal of a small piece of tissue for diagnosis.
Testing for HPV
There currently is only one FDA-approved, commercially available test for HPV, the Hybrid
Capture, produced by Digene Corporation. Like the Pap test, the HPV test examines cells taken
from the cervix (or anus). There is now an increasing number of laboratories around the country to
which doctors can send specimens for HPV analysis. The HPV test checks directly for genetic material
(DNA) of HPV, and may be used to determine which women with a borderline abnormal Pap test result
known as ASC-US (atypical squamous cells of undetermined significance) are most likely to have
underlying precancerous or cancerous changes on their cervix. For women diagnosed with LSIL or
HSIL, the test will almost always be positive, so HPV testing does not generally provide additional
helpful information for women with those results.
The HPV test looks specifically for certain high-risk HPV types that are known to be associated
with cervical cancer. A positive test means that one of the types of HPV being tested is present,
and the amount is enough to cause an infection.
It is not known how often women should get an HPV DNA test. Use of HPV DNA testing to extend Pap
test screening intervals is under active consideration.
Transmission of HPV
It is very easy to spread the virus to a sexual partner. Although using a condom is a good idea to
prevent transmission of other infections or diseases, condoms may not protect sexual partners from
genital HPV infections. HPV infections usually are not limited to the penis or the vagina. The
infection can occur on the skin in the genital area, such as the scrotum, vulva, anus, or the skin
between the anus and the genitalia - areas that are not protected with normal condom use. It is not
known if transmission can occur when the virus levels are very low or undetectable.
Treatment of HPV Infection
Although there is currently no medical cure to eliminate HPV, the high-grade cell changes
(HSILs) and warts caused by HPV can be treated. Methods used to treat HSILs include cryosurgery
(freezing that destroys tissue), 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, topical treatments such as Podofilox and Imiquimod may
be applied to destroy genital warts. LSILs often are not treated, as most of these cell changes
will go away on their own.
Current Research on HPV and Cervical Cancer
The ASCUS/LSIL Triage Study (ALTS), a major study organized and funded by the National
Cancer Institute (NCI), has evaluated different management approaches for women with mildly abnormal
Pap test results. Findings from ALTS demonstrate that testing cervical samples for HPV is an
excellent option to help direct follow-up for women with an ASC-US Pap test result.
Researchers at NCI and other sites are studying how HPVs cause precancerous changes in normal
cells and how these changes can be prevented. They are using non-infectious HPV-like particles
created in the laboratory as preventive vaccines against the viruses. Investigators are conducting
clinical trials to test vaccines for certain papillomaviruses, such as HPV-16 and HPV-18, which are
known to be particularly high-risk for the development of cervical cancer. It is hoped that a vaccine
will be available within 10 years to prevent the most common HPV infections.
More information about Sexual Health:
Herpes Information
What is genital herpes?
A Primer on HPV
What is human papillomavirus?
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