A federal advisory panel yesterday unanimously recommended that the Food and Drug Administration approve a vaccine that has been shown to prevent cervical cancer, the second most common cause of cancer among women worldwide.

The FDA almost always follows the recommendations of its advisory panels, and is expected to do so in this case, probably by June 8.

"It is common sense, good medicine and a groundbreaking step forward in the fight against cancer," said Cecile Richards, president of the Planned Parenthood Federation of America.

Tests in more than 17,000 girls and women have shown that the vaccine, called Gardasil, is nearly 100 percent effective in blocking cervical cancers caused by the sexually transmitted human papilloma virus.

Guardasil prevents against four strains of human papilloma virus. Two strains are thought to be responsible for 70 percent of the 15,000 cervical cancers diagnosed and the 4,000 deaths caused by it in the United States each year. Worldwide, 400,000 women are diagnosed with cervical cancer each year and 200,000 die of it. The other two strains are behind about 50 percent of genital wart cases.

Human papilloma virus, commonly called HPV, is the most common sexually transmitted disease in this country, with about 20 million people infected.

The vaccine is most effective when given to girls before they become sexually active, which would require administration between the ages of nine and 13.

Dr. Monica M. Farley of the Emory University School of Medicine, acting chair of the advisory panel, said that the vaccine's manufacturer, Merck & Co., had submitted "very impressive data" to the panel about the vaccine's efficacy and that FDA approval would be a "wonderful good step" toward controlling cervical cancer.

Public health groups, nine of whom testified before the panel yesterday, were unanimous in recommending approval of the vaccine.

UNIVERSAL VACCINATION

A vaccine utilization committee of the Centers for Disease Control and Prevention is scheduled to meet on June 29, at which time it could vote on whether to recommend universal use of Gardasil in females. A draft proposal recommends vaccinating all girls ages 11 and 12.

Requirements for its use, however, can only be mandated by individual states. In some, like California, such a mandate would require passage of legislation, said Dr. Eileen Yamada of the state Department of Health Services.

Even if it should become a requirement, added Wendy Wright, president of Concerned Women of America, all states allow children to opt out of mandatory vaccinations for medical or other reasons.

Some conservative religious groups have expressed concerns about the vaccine, arguing that it may send an implicit message to young girls that sex is OK.

The opposition of such groups was responsible for the only recent instance in which FDA has not followed the recommendation of an advisory committee: a similar panel recommended approval of Plan B, the so-called morning-after pill, in December 2003, but the agency still has not acted.

None of the groups chose to speak before the panel in opposition to the approval, and many representatives indicated that they simply would not have their daughters vaccinated with Gardasil.

"We welcome the vaccine," said Pete Sprigg of the Family Research Council. But, he added, "Decisions about sexual health are tied up in personal values and parents should have the right to transmit personal values to their children."

USE IN MALES

The panel did not consider whether the vaccine should be used in males because there is not yet enough data to support its efficacy. The viruses cause rare cases of cancer of the anus and the penis in males, and vaccination of boys would also help prevent spread of the viruses among women, experts said.

Dr. Eliav Barr of Merck told the panel that data about the efficacy studies in males should be available in 2008, at which time the company would seek approval for that group.

Experts expect many older women to take the vaccine as well, but it is not recommended for those who might be pregnant because the initial trial found a few birth defects in the women who received it.

The panel stressed that Gardasil does not eliminate the need for cervical cancer screening, such as the pap smear test, because the vaccine does not protect against all HPV strains.

Some experts had reservations about the practicality of the vaccine that were unrelated to its efficacy or morality. Gardasil is expected to cost as much as $500 and must be administered in three separate injections over the course of six months.

The cost may put it out of the reach of many of the families in which girls are at the highest risk of contracting the virus, and the need for three separate physician visits could severely limit its use.

"Cost is really going to present public health agencies with a significant challenge," said Jeffrey Duchin, head of immunizations for the Seattle & King County Public Health Department. The CDC committee could recommend federal subsidies to make Gardasil available to low-income families.

Gardasil was originally developed by Dr. Douglas Lowy of the National Cancer Institute. It is made of virus-like particles, grown in yeast, that contain all of the surface proteins of the papilloma viruses, but none of their genetic information.

$2.8B IN SALES POSSIBLE

If approved, Gardasil would be the second vaccine to protect against cancer. Hepatitis B vaccines have previously been shown to protect against liver cancer.

If the vaccine is approved only for girls, analysts expect annual sales to top $720 million. If it is widely used by boys and women, sales could rise to $2.8 billion a year.

GlaxoSmithKline Biological is developing a similar vaccine, called Cervarix, that protects against two strains of the papilloma virus and that has also proved highly effective. The company has said it will ask FDA for approval later this year.