HPV Tests Urged in Addition to Pap Smears
Study says both tests every two years will save lives and money
TUESDAY, May 7, 2002 (HealthDayNews) -- Lives and money could be saved if, along with a Pap smear, women were screened every two years for a virus closely connected to cervical cancer.
That's the conclusion of a mathematical model, which says the two tests combined would prevent 225 cases of invasive cancer for every 100,000 women, and cut the death rate by 59 percent.
The study, appearing in tomorrow's issue of the Journal of the American Medical Association, says the two-pronged screening method is cost-effective as well as lifesaving.
A second study in the same journal, which also uses a mathematical model, says testing for the genetic material of the human papillomavirus (HPV), a sexually transmitted virus that researchers believe to be a major cause of the cancer, would also be money well spent.
There are differing opinions about the Pap smear test, the standard way of catching cervical cancer early. Some 50 million American women have Pap tests each year. Perhaps 2.5 million of those tests come back with abnormal, but not clearly cancerous, results.
The first model, produced at the Lombardi Cancer Center of Georgetown University, concludes that "maximal savings in life could be achieved by screening every two years from age 20 to death with a combination of HPV and Pap tests."
It says that HPV testing is highly sensitive, and cost only about $5.
The second model, produced at the Harvard School of Public Health, concludes that looking at the genetic material of the HPV to determine whether it is a high-risk strain for cervical cancer is the most cost-effective strategy.
"There are four options currently in medical practice," says Jane H. Kim, a student at the Harvard Center for Risk Analysis who is lead author of that paper. "One is to have the woman come back for repeat Pap smears six months and 12 months later. Another is to have colposcopy, a test that often involves a biopsy. A third is to ignore the results. The fourth is DNA testing of the HPV strains."
The last strategy is best, Kim says, not only because it is more effective and less costly than the others, but also because it reduces the anxiety women feel when told they have a test that might be positive.
As it happens, that conclusion bolsters the guidelines for follow-up testing recently issued by several medical organizations, says Debbie Saslow, director of breast and cervical cancer for the American Cancer Society. Those organizations, led by the American Society for Colposcopy and Cervical Pathology, say detailed HPV testing is the most cost-effective strategy.
But those guidelines can be controversial, Saslow adds.
"Because HPV testing is new, there are a lot of unknowns about it," she says. "One of them is the issue of counseling patients, and how women would react to the news. A lot of doctors said they were so uncomfortable about the subject that they would not even participate in studies."
The issue of HPV testing as part of a screening procedure is even more complex, Saslow says. One complication is the HPV test has not yet been approved by the U.S. Food and Drug Administration (FDA) for use in screening. It does have FDA approval for follow-up testing, and an FDA advisory panel recently recommended its approval for screening, but the agency has not acted yet.
Timing is also an issue. The FDA panel recommended a Pap test and HPV test every three years. The Georgetown study says it should be done every two years. "The big issue is how often you should screen," Saslow says.
The great advantage of the two computerized studies is that they help clarify the issues in a field where real-life trials are just about impossible, says Dr. David H. Mark, a contributing editor to the medical journal who wrote an accompanying editorial.
"Modeling is the only way we can get ideas about the value of comparative methods of screening," Mark says. "A controlled study couldn't be done, where you actually followed people to look at the outcome. It would be too expensive, and take too long."
The computer-generated strategies could be tweaked a little to improve their effectiveness, Mark says, notably by stressing frequent screening for women at high risk of infection with HPV, which is spread by sexual activity.
"This is another instance where you have the science available before you have all the answers, and don't know what to do with it," Saslow says.
What To Do
The current U.S. recommendation is that all sexually active women have a cervical cancer screening test annually. If the results are negative for several years, the frequency can be reduced, but a test should be done at least once every three years. It's different in Europe, Saslow notes: Authorities there recommend a test every five years.