Cervical cancer shots less cost-effective with age, U.S. study shows

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By Mike Stobbe
THE ASSOCIATED PRESS

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ATLANTA - An expensive vaccine aimed at preventing cervical cancer makes sense for young teens when it comes to cost-effectiveness, but not for women in their 20s, contends a new report.

The vaccine against the HPV virus was licensed the U.S. in 2006 for use in girls and women ages nine to 26. Health officials recommend it for girls at age 11 or 12, and some doctors offer it to women in their 20s in "catch-up" vaccination campaigns.

The maker of the Gardasil vaccine, Merck & Co., also wants to market it to women ages 27 to 45, but so far the U.S. Food and Drug Administration has denied that request.

In Canada, all provinces have approved the vaccine for young girls. However, the HPV vaccine has become an issue of debate for Catholics everywhere because the human papilloma virus is sexually transmitted. At least one Catholic school district in Ontario voted narrowly to no longer allow the shots on school premises, and six Catholic bishops in Alberta are urging parents to learn more about the vaccine before allowing their daughters to be immunized.

The U.S. government-funded study found the HPV vaccine is very cost-effective when given to girls at age 12, but raises questions about the value of pushing for vaccinating adults.

Two researchers at the Harvard School of Public Health did the study, one of the most sophisticated analyses of the issue so far. Results are in the latest New England Journal of Medicine.

Gardasil is given in three doses over six months and costs about $375 in the U.S. It targets the two types of HPV, or human papillomavirus, believed to be responsible for about 70 per cent of cervical cancer cases, and two other types that cause most genital warts. The virus spreads through sex.

Health officials say it's best to give the shots to girls at age 11 or 12, before they begin having sex. Some parents think that age is too young for a vaccination campaign against a sexually transmitted disease.

But that is when the shots make the most economic sense, the researchers found.

They used computer models to predict the health outcomes of girls and women who get the vaccination as well as Pap tests or other screenings, which are still recommended for vaccine recipients. Their calculation included the cost of the vaccine, screenings and treating cervical cancer and other illnesses targeted by the vaccine.

To determine cost-effectiveness, the researchers used widely accepted economic measures of how much society is willing to pay to extend the life of a person by a year. They set a figure of $43,600 per year for the Gardasil vaccination of each 12-year-old girl, well below the $100,000 mark seen as an upper range for cost-effectiveness.

That assumes the vaccine gives lifetime protection -- something doctors don't know is true because the shot is too new.

"Their base-case assumptions are quite optimistic," wrote Dr. Charlotte Haug, a Norwegian physician, in an editorial that accompanies the study.

The figure would rise if a booster shot is needed, but would still be under the cost-effective threshold, experts said. Another caveat: Costs could rise if there is an increase in the types of cancer-causing HPV not included in the vaccine.

Vaccinating "catch-up" campaigns for women in their 20s, however, would not be cost-effective, the researchers said. They didn't calculate cost-effectiveness of vaccinating women ages 27 to 45, but a trend seems clear, said Jane Kim, the study's lead author.

"As you get older, the vaccine becomes less cost-effective," she said.

Experts believe that the earlier a female is vaccinated, the better the odds she will avoid HPV-caused cervical disease, thus lowering health-care costs down the road.