To Cancer : Complementary and Integrative Therapies of Cancer.

Most cervical cancers are caused by the sexually transmitted infection human papillomavirus (HPV). Widespread HPV immunization, however, could reduce the impact of cervical cancer worldwide. Here, Bobbie Gostout, M.D., an HPV infection expert and gynecologic surgeon at Mayo Clinic, Rochester, Minn., discusses the cervical cancer vaccine.

What does the cervical cancer vaccine do?

Various strains of HPV, which spread through sexual contact, cause most cases of cervical cancer. Two cervical cancer vaccines have Food and Drug Administration (FDA) approval in the U.S. — Gardasil and Cervarix. Both vaccines can prevent most cases of cervical cancer if given before a girl or woman is exposed to the virus.

In addition, both can prevent most vaginal and vulvar cancer in women, and Gardasil can prevent genital warts in women and men.

Who is the cervical cancer vaccine for and when should it be given?

The cervical cancer vaccine is recommended for girls ages 11 to 12, although it may be given to girls as young as age 9. It’s important for girls to receive the vaccine before they have sexual contact and are exposed to HPV. Once a girl or woman has been infected with HPV, the vaccine may not be as effective.

In addition, Gardasil can be given to boys between ages 9 and 26 to help prevent genital warts.

The Centers for Disease Control and Prevention (CDC) recommends catch-up immunization for girls and women ages 13 to 26 who haven’t received the vaccine or who haven’t completed the full vaccine series. The cervical cancer vaccine isn’t recommended, however, for women older than age 26.

Both vaccines are given as a series of three injections over a six-month period. The second dose is given one to two months after the first dose, and the third dose is given six months after the first dose.

The cervical cancer vaccine isn’t recommended for pregnant women or people who are moderately or severely ill. Tell your doctor if you have any severe allergies, including an allergy to yeast or latex.

Why are three doses of the cervical cancer vaccine needed?

Researchers don’t yet know what antibody levels provide adequate protection from HPV. In early clinical trials, researchers observed that women’s antibody levels continued to increase 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 and attempt to get the greatest HPV protection for the longest possible time — years or even decades.

Over time, however, researchers may find that three doses of the vaccine aren’t necessary — or that a booster shot is needed years later.

Does the cervical cancer vaccine offer benefits if you’re already sexually active?

Yes. In clinical trials, Gardasil and Cervarix were effective in groups of sexually active women age 26 or younger, some of whom had already been infected with one or more types of HPV. However, Gardasil and Cervarix only protect you from specific strains of HPV to which you haven’t been exposed. The more sexual partners you’ve had, the greater your chance of having been exposed to multiple types of HPV.

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