Common Sexually Transmitted Disease
Genital human papillomavirus (HPV) is the most common sexually transmitted infection (STI). The virus infects the skin and mucous membranes. There are more than 40 HPV types that can infect the genital areas of men and women, including the skin of the penis, vulva (area outside the vagina), and anus, and the linings of the vagina, cervix, and rectum. You cannot see HPV. Most people who become infected with HPV do not even know they have it.
HPV includes hundreds of virus types, 30 to 40 of which can infect the genital area. Genital HPV can be low risk or high risk. The low-risk types can cause genital warts and mild Pap test abnormalities. High-risk types can cause cell changes that lead to cervical cancer.
HPV is especially common among younger women. An estimated 28 percent to 46 percent of American women under age 25 carry the virus. If you're older than 30, your doctor may recommend an HPV test along with your Pap test. Like the Pap test, an HPV test involves collecting cells from the cervix with a brush or swab. The aim is to detect high-risk types of HPV that may lead to cervical cancer.
The good news is that most HPV infections don't progress to cancer. If abnormal cells develop, routine Pap tests usually can detect them at an early stage so they can be treated. Regular Pap tests are important because women with early cervical cancer generally don't have any symptoms.
Most women should have Pap tests beginning at age 21 or three years after they become sexually active. Your doctor will recommend rechecks based on your age and Pap test results.
The Pap test, also called a Pap smear, checks for changes in the cells of your cervix. The cervix is the lower part of the uterus (womb) that opens into the vagina (birth canal). The Pap test can tell if you have an infection, abnormal (unhealthy) cervical cells, or cervical cancer.
First, Pap tests don't need to be a yearly event for every woman. The American Cancer Society recommends that women over 30 who've had normal Pap results for three years can limit screening to once every two or three years. Women over age 70 who've had three normal tests in a row, no abnormal tests in 10 years and no new risk of cervical cancer (such as a new sexual partner) can opt to forgo cervical cancer screening.
Researchers are evaluating a human papillomavirus (HPV) screening as a way to detect cervical cancer earlier. Like the Pap test, the HPV test is conducted on a sample of cells collected from the cervix. The test looks for evidence of the HPV genetic material that can lead to cancer.
Two studies published in 2007 showed that the HPV test has promise. One found that the HPV test was nearly 40 percent better at identifying women with precancerous or cancerous abnormalities than the Pap test. The second study looked at using HPV and Pap screens together. This approach helped identify causes of precancerous lesions earlier than the Pap alone.
There are concerns with the HPV screen, too, including a higher percentage of false-positive results, where women who received positive HPV tests were referred for further tests that did not show any signs of cancer. HPV screening also identifies more precancerous lesions that are slow to develop into cancer or never develop into cancer.
For now, most doctors don't support HPV testing as a primary screening tool until there's more evidence to justify replacing the Pap test. Depending on a woman's age and risk factors, the HPV test may be ordered after an uncertain Pap test or, in some circumstances, may be used in conjunction with a Pap test. Women should ask their doctor which screening is best.
HPV Vaccines and Human Papillomavirus
HPV vaccines protect against a very common sexually transmitted virus called HPV or humanpapillomavirus. HPV infects at least 50% of sexually active people at some point in their lives. The virus often clears on its own. If it persists, it can lead to cervical and other cancers and to genital warts.
One HPV vaccine, Gardasil, was licensed for use by the FDA in 2006. In September 2008, the FDA announced it may also be used to prevent some cancers of the vulva and vagina in girls and women ages 9-26.
Another HPV vaccine, Cervarix, is expected on the market soon.
Gardasil, the two-year-old vaccine that's designed to prevent cervical cancer, is safe, U.S. officials said Wednesday.
The U.S. Centers for Disease Control and Prevention's Immunization Safety Office said a study of 370,000 doses given to girls and young women over the past two years found no evidence that the vaccine causes an increased risk of blood clots or other serious conditions, Bloomberg News reported.
First HPV Vaccine on the Market: Gardasil
Gardasil, the HPV vaccine made by Merck & Co., was licensed for use in June 2006. It targets four types of HPV: 6, 11, 16 and 18. Types 16 and 18 lead to cervical cancer. HPV 6 and HPV 11 cause about 90% of genital warts.
The vaccine contains a virus-like particle but not the actual virus. Three doses are given over six months.
The cost is $120 per dose. Insurance coverage is common within the recommended age ranges. The federal Vaccines for Children Program covers the vaccine for those under age 19 who qualify. No serious HPV vaccine side effects have been found. Sometimes soreness occurs at the injection site.
Who Should Get Gardasil?
The vaccine should be given to girls at ages 11 to 12, according to recommendations from the American Academy of Pediatrics and the CDC. The vaccine is best given at a young age, before sexual activity begins and before exposure to HPV.
The recommendations note that girls as young as 9 can get the vaccine, and females up to age 26 who didn't get it as youngsters. The vaccine is also being studied in older women.
The jury is still out on whether the vaccine is effective in boys. More research needs to be done. Scientists don't yet know if an HPV vaccine will protect boys from genital warts or if the vaccine can prevent boys from transmitting HPV to female partners.
In the Wings: Cervarix
Another HPV vaccine, Cervarix, is under FDA review. In studies, this vaccine, like Gardasil, protected against types 16 and 18, which cause 70% of cervical cancers. Cervarix also protects against HPV types 31 and 45, which also cause cervical cancer, according to the manufacturer, GlaxoSmithKline.
Three doses are given over six months.
Long-Term Protection, Not Cure
The vaccines are not an HPV cure. But both vaccines have been shown to provide protection for five years, according to research presented at the 2007 annual meeting of the American Association for Cancer Research. New research also suggests that Gardasil, like Cervarix, also protects against HPV types 45 and 31, which account for about 10% of cervical cancers.
HPV vaccination doesn't mean women can skip their Pap tests. Neither vaccine protects against all the types of HPV that cause cervical cancer. So women still need to schedule Pap tests.