Amount of virus sets cancer risk.

Physicians may soon have a way of determining which women with "abnormal" Pap smears will develop cancer of the cervix. Researchers at the Albert Einstein College of Medicine in New York City have found that human papillomavirus (HPV) infections that persist over time are far more likely to develop into cervical cancer than transient infections with the virus.

Pap smears first gained acceptance in the 1950s as a way of identifying abnormalities in cervical cells--known as dysplasia--before they developed into invasive cancers. In the 1980s, researchers learned that HPV, which causes warts, is involved in approximately 90 percent of all cervical cancers, as well as a great many noncancerous changes.

But because some 50 percent of all mildly dysplastic lesions, or collections of abnormal cells, regress back to normal, physicians discovering HPV-associated cervical lesions had to decide whether close monitoring or aggressive therapy, such as cryotherapy, laser therapy, or surgery, was appropriate. "Clinicians may be overtreating women for [abnormal Pap smears] for a variety of reasons," says study collaborator Gloria Y.F. Ho.

To help resolve this quandary, Ho and her colleagues monitored 70 female volunteers with mild to moderate dysplasia every 3 months for 15 months. At each visit, the researchers gave the women a Pap test, examined their cervices under a microscope, and tested cells from the lesions for the virus' DNA.

As the researchers report in the Sept. 20 Journal of the National Cancer Institute, 30 percent of all moderate dysplasia spontaneously regressed; moreover, the amount of viral DNA present enabled the team to identify the lesions that would regress. "Women whose lesions contained large amounts of HPV were likely to have their lesions persist," says Ho.

Mark H. Schiffman of the National Cancer Institute in Bethesda, Md., who wrote a commentary accompanying the report, told Science News that the New York group's work is a "satisfying piece of evidence that the virus and the [cervical] changes are so tightly linked that they are in fact the same thing."

Ho points out that the sophisticated DNA analysis her group used isn't routinely available to clinicians, but since the largest amounts of HPV were associated with persistent lesions, physicians could confidently monitor patients for the virus with currently available tests for several months before deciding to treat the condition more aggressively.