A vaccine that offers protection from the virus responsible for most cases of cervical cancer is the latest addition to the official childhood immunization schedule. Here, Bobbie Gostout, M.D., an HPV infection expert and gynecologic surgeon at Mayo Clinic, Rochester, Minn., provides insight into this revolutionary cervical cancer vaccine.
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What's the significance of the cervical cancer vaccine?
The cervical cancer vaccine (Gardasil) is the first vaccine ever designed to prevent a cancer. In the United States — where cervical cancer strikes about 10,000 women a year and causes up to 4,000 deaths — the impact of the cervical cancer vaccine will be tremendous. Worldwide, the impact may be even greater. According to the World Health Organization, there were 500,000 new cases of cervical cancer in 2005.
The tragedy of cervical cancer is that it often strikes when a woman is still young. She may be trying to raise her family or maybe she hasn't had children yet. Cervical cancer treatment may make future fertility impossible. And even with treatment, cervical cancer is a leading cause of cancer death in women.
What does the cervical cancer vaccine do?
Various strains of the human papillomavirus (HPV), which spreads through sexual contact, are responsible for most cases of cervical cancer. The cervical cancer vaccine specifically blocks two cancer-causing types of HPV — types 16 and 18 — to get at the root cause of the cancer. In essence, the cervical cancer vaccine stops cervical cancer before even the first step can begin.
The cervical cancer vaccine also blocks HPV types 6 and 11, which are not associated with cervical cancer but are associated with genital warts and mild Pap test abnormalities. A study presented by Gardasil's manufacturer in September 2007 says that the vaccine provides partial protection from a number of additional strains of HPV as well.
When should the cervical cancer vaccine be given?
The cervical cancer vaccine is recommended for girls ages 11 to 12, although it may be used in girls as young as age 9. This allows a girl's immune system to be activated before she's likely to encounter HPV. Vaccinating at this age also allows for the highest antibody levels. The higher the antibody levels, the greater the protection.
The vaccine is given as a series of three injections over a six-month period. The second dose is given two months after the first dose, followed four months later by the third dose.
Experts at the Centers for Disease Control and Prevention (CDC) recommend a catch-up immunization for girls and women ages 13 to 26 who haven't been vaccinated or who haven't completed the full vaccine series. By vaccinating this catch-up group, as well as the younger girls, we'll see the positive effects of the cervical cancer vaccine that much sooner.
Why are three doses of the cervical cancer vaccine needed?
We really don't know that three doses are necessary because we don't know what antibody levels provide adequate protection from HPV. In early clinical trials, researchers observed that the antibody levels in women continued to go up with each of the three doses of the vaccine. Since antibody levels inevitably fall once you stop getting a vaccine, it makes sense to start with high antibody levels to get the greatest HPV protection for the longest possible time — years or even decades.
Over time, we may find that three doses of the vaccine aren't necessary, or we may discover that a booster shot is needed years later. Those are details we just don't know right now.
Does the vaccine offer benefits if you're already sexually active?
Yes. In clinical trials, the vaccine was effective in a group of sexually active women age 26 or younger, some of whom had already been infected with one or more types of HPV. There's a caveat, however. The cervical cancer vaccine blocks HPV types 6, 11, 16 and 18, but only if you haven't been exposed to those particular types of HPV. The more sexual partners you've had, the greater your chance of having been exposed to multiple types of HPV — including HPV types 6, 11, 16 and 18.
Some experts encourage women ages 18 to 26 to review their sexual history with their doctors to determine if there's a reasonable chance of benefiting from the vaccine. Others support the CDC's recommendation of universal vaccination for women ages 18 to 26.
Does the vaccine carry any health risks or side effects?
The cervical cancer vaccine has proved to be remarkably safe. The most common complaint is soreness at the injection site, the upper arm. Low-grade fever or flu-like symptoms also are common. But the effects are usually mild. No one in the clinical trials discontinued the vaccination series because of side effects.
Is the cervical cancer vaccine required for school enrollment?
The cervical cancer vaccine is part of the routine childhood vaccines schedule. Whether or not a vaccine becomes a requirement for school is decided on a state-by-state basis. Remember, the greater the number of girls and women vaccinated, the greater the benefit we'll see from the cervical cancer vaccine.
Will women still need to have Pap tests?
Absolutely. And this is a really important point. The cervical cancer vaccine isn't intended to replace Pap tests. Routine screening for cervical cancer through regular pelvic exams and Pap tests remains an essential part of a woman's preventive health care.
What can you do to protect yourself from cervical cancer if you're not in the recommended vaccine age group?
HPV spreads through sexual contact. To protect yourself from HPV, use a condom every time you have sex. It's also important to limit your number of sexual partners. Not smoking helps, too. Smoking doubles the risk of cervical cancer.
To detect cervical cancer in the earliest stages, see your doctor for regular pelvic exams and Pap tests. Seek prompt medical attention if you notice any signs or symptoms of cervical cancer — vaginal bleeding after sex, between periods or after menopause; foul-smelling watery or bloody vaginal discharge; pelvic pain; or pain during sex.
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