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Girls should get the new vaccine for human papilloma virus (HPV) at age 11-12, the American Cancer Society says in new guidelines issued Friday.

HPV is a very common virus. Some types of HPV are sexually transmitted, and these can cause cervical cancer and other types of cancer, as well as genital warts.

The vaccine currently available, called Gardasil, protects against 2 types of HPV that cause about 70% of cervical cancers, and 2 other types that cause 90% of genital warts. It is given as a series of 3 shots over the course of 6 months. Other HPV vaccines are also being tested.

But screening will still be an important part of cervical cancer prevention, even in people who have been vaccinated, the guidelines say. They are published in the latest issue of the ACS journal CA: A Cancer Journal for Clinicians.

The complete ACS recommendations address several different groups:

• Routine HPV vaccination is recommended for girls aged 11-12 years.
• Girls as young as 9 years old may be vaccinated.
• The vaccine is also recommended for girls 13-18 years old to catch up on missed shots or to complete the series of shots.
• There is not yet enough information to recommend for or against vaccinating women 19-26 years old, so these women should discuss vaccination with their doctor.
• The HPV vaccine is not recommended at this time for women over age 26.
• The HPV vaccine is not recommended at this time for boys or men.
• Women should continue to be screened for cervical cancer according to ACS guidelines, regardless of whether they have gotten the HPV vaccine.

The new recommendations are in line with those issued by federal health officials after the vaccine was approved last summer.

Cervical cancer screening with the Pap test has greatly reduced the incidence of this cancer in the United States. The greatest impact of the vaccine is likely to be in groups where screening levels are low, such as in medically underserved populations. The vaccine may prove especially helpful in other countries where cervical cancer screening is not routinely done.

Giving the vaccine to young girls is important, the new guidelines say, because it works best when given to people before they ever become infected with HPV. Because the types of HPV that cause cervical cancer are sexually transmitted, girls should get vaccinated well before they become sexually active.

Surveys of US teens show that nearly a quarter of them have had sex by age 15, and 70% have had sex by age 18.

Most people become infected with HPV at some point in their lives, but the infection usually clears up on its own without ever causing any symptoms. Only rarely does the infection linger in the body and cause cancer. The American Cancer Society estimates there will be about 11,150 cases of cervical cancer in the US in 2007. About 3,670 women will die from the disease.

Widespread vaccination promises to reduce the number of people with diseases caused by HPV, the guidelines say. Over the long term (it can take up to 20 years for an HPV infection to cause cervical cancer) that will mean fewer cases of cervical cancer. In the short term, it will mean fewer cases of genital warts, and less need for procedures (like biopsies) used to treat pre-cancerous changes in the cervix.

But being vaccinated will not eliminate the need for cervical cancer screening, the guidelines stress.

For one thing, the vaccine only protects against 2 types of HPV that cause cervical cancer; there are around a dozen other types that also can cause this disease. The vaccine also doesn't protect women if they are already infected with one of HPV types targeted by the vaccine.

Women who are vaccinated could therefore still develop cervical cancer, and screening is the best way to prevent that from happening. Screening with the Pap test can detect dangerous changes in the cervix before they ever turn into cancer, or at least find cervical cancer at an early stage, when it is easier to treat.

It also isn't known yet how long the vaccine will provide protection, or if booster vaccinations may be needed at some point. Clinical trials have followed women only for about 5 years.

Citation: " American Cancer Society Guideline for Human Papillomavirus (HPV) Vaccine Use to Prevent Cervical Cancer and Its Precursors " Published in the Jan./Feb. 2007 CA: A Cancer Journal for Clinicians (Vol. 57, No. 1: 7-28). First author: Debbie Saslow, PhD, American Cancer Society.