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TUESDAY, Aug. 12, 2003 (HealthDayNews) -- Even the most successful cervical cancer vaccine won't make screening with Pap smears unnecessary.
That's the conclusion of a study appearing in the Aug. 13 issue of the Journal of the American Medical Association.
Researchers from Duke University looked at preliminary data on cervical cancer vaccines that are currently in clinical trials and used a mathematical model to predict how the vaccine and Pap smears could be used most effectively. They found that if the vaccine was given before a young woman became sexually active, it would likely save money to delay the onset of screening for cervical cancer until the age of 24.
"We examined the cost-effectiveness of three different strategies: vaccination only, vaccination and screening, and screening only," says study author Shalini Kulasingam, a research associate in obstetrics and gynecology at Duke University Medical Center. "We found the most cost-effective strategy, if an effective vaccine was available and used in combination with screening, was to vaccinate young girls prior to the onset of sexual activity and then to delay the onset of screening."
The Pap smear is the current screening method used to detect cervical cancer. The American Cancer Society recommends that women start getting Pap smears within three years of becoming sexually active, but no later than 21 years of age. After that, women should have annual screenings until the age of 30. After that, if a woman has had normal results on previous Pap smears, she can go two to three years between tests.
Screening for cervical cancer is important because this type of cancer rarely has symptoms before it has spread to other parts of the body. The National Cancer Institute estimates that 15,000 women are diagnosed with cervical cancer every year.
The sexually transmitted human papillomavirus (HPV) is a known cause of cervical cancer. There are at least 13 high-risk types of HPV believed to cause cervical cancer, according to Kulasingam. The vaccines currently in clinical trials cover two of the more common types of HPV, but not all of them.
The researchers compared costs and life expectancy of vaccination only, vaccination and screening, and screening alone. When looking at screening, the researchers looked at conventional screening. They also modeled screening at one-, two-, and five-year intervals, and varied the age at which screening started.
The mathematical model used assumed that women were vaccinated at the age of 12. The study points out that, in reality, parents may not want to have their child vaccinated against a sexually transmitted disease at such a young age.
Assuming the vaccine is effective, the researchers found initial screening could be delayed until a woman was 24 and then done every other year.
Vaccination alone, however, was not a cost-effective strategy, according to the study. The current versions of the vaccine will cover only one or two of the high-risk types of HPV. Also, Kulasingam points out that long-term efficacy data isn't available on the vaccine.
"Regardless of the vaccine that becomes available, women will still need to be screened," she says.
Dr. Mark Werner, an obstetrician and gynecologist at William Beaumont Hospital in Royal Oak, Mich., agrees. "We probably won't know for many years what the best screening interval is. Initially, I'm sure we'll still do once-a-year Pap smears."
This study, he says, is a first look at the many questions a vaccine will bring up, such as the best age to give the vaccine or how often it needs to be given.
But, he adds, "The vaccine is exciting. It will save lives for sure and maybe reduce some health-care costs."
More information
To learn more about cervical cancer, visit the National Cancer Institute. For information on preventing the disease, go to the American Cancer Society.
