Beyond the Pap

By Christine Gorman

For more than 50 years, a regular Pap test has been a woman's best defense against cervical cancer. By taking tissue samples from the cervix--the "neck," or outer opening, of the uterus--a doctor can usually tell that something is wrong before the cancer has a chance to fully develop or spread. Now researchers are eyeing a new gene-based test that they believe is better than the Pap test at identifying precancerous and malignant changes in the cervix--and could even replace it. But don't cancel your next gynecologic exam just yet. A lot more work needs to be done before the new test is ready for widespread use.

Scientists have known for some time that virtually all cases of cervical cancer are triggered by a family of viruses called human papillomavirus, or HPV. Most women who become infected with HPV are able to shake off the virus and suffer no apparent long-term consequences to their health. But a few women develop a persistent infection that can, for reasons that are not entirely clear, eventually lead to cancerous changes in the cervix. (One thing we do know: the risk of developing cervical cancer increases dramatically for women who have HPV and smoke.)

Now researchers at the Digene Corp. of Beltsville, Md., have developed a test that detects an active HPV infection by looking for its genetic by-products in the vagina. The HPV test was better than the standard Pap test at finding cervical cancer at any stage, according to two studies published in last week's Journal of the American Medical Association. So far, so good. Unfortunately, the test's false-positive rate--how often it indicated that there was a problem when none existed--was almost twice as high as that for the Pap smear. In these cases, a biopsy of the woman's cervix showed no sign of disease.

And that's the crux of the problem. How many women should undergo what is, when it comes right down to it, unnecessary treatment to find a few more cases of cervical cancer? Shouldn't health officials focus instead on making sure that more women undergo regular Pap-smear examinations? After all, Pap smears, though far from perfect, have helped dramatically lower the death toll from cervical cancer--taking it from the No. 1 cause of death due to cancer in American women to the 10th.

Complicating matters is the fact that HPV is a very common infection. In some parts of the U.S. as many as half of all women under age 35 have an active case. Yet 99 out of 100 women who are HPV-positive will never get cervical cancer, estimates Dr. Joanna Cain, chair of the department of obstetrics and gynecology at Penn State University College of Medicine in Hershey, Pa., and vice president of the American College of Obstetricians and Gynecologists. "If those 99 women live their lives as if they're going to develop cancer," she says, "we're not necessarily doing them any good."

At present, the HPV test is approved in the U.S. only to help resolve ambiguous results from a Pap-smear test. Many gynecologists believe that HPV will eventually replace the Pap. But they're not willing to abandon it without a lot more detailed information--and neither should you.

For more information on cervical cancer and HPV, visit time.com/personal You can e-mail Christine at gorman@time.com