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HPV
Testing
May
Be Useful in
Cervical
Cancer Screening
Testing for the human papillomavirus (HPV) can accurately identify
many precancerous changes in the cervix and may be a useful
screening tool in some populations, according to a study appearing
in the Journal of the American Medical Association (JAMA)*.
Previous studies have shown that certain types of HPV cause
most cervical cancers, raising the possibility that testing
for these HPV types may be one way to screen for the disease.
However, there has been uncertainty about how reliable and accurate
HPV testing would be.
The purpose of this study was to provide data on how HPV testing
would perform as a screening tool in a population at high risk
for cervical cancer. The research team, including investigators
from the United States and Costa Rica, evaluated HPV testing
in a randomly selected group of 8,554 women in Guanacaste Province,
Costa Rica, where cervical cancer rates are high. The HPV tests
used were the Hybrid Capture Tube test and its successor, Hybrid
Capture II**, which detect HPV DNA. Women in the study were
also screened using other methods, including the conventional
Pap test.
The Hybrid Capture II test accurately detected a high proportion
of the precancerous, high-grade lesions as well as all cases
of cervical cancer in this population. Using an HPV level of
1 pg/ml (1 picogram of HPV DNA per milliliter of solution) as
cutpoint – any test result of one or above was considered HPV
positive – the researchers found that the test detected 88.4
percent of the precancerous lesions and 100 percent of the cancers.
At the 1 pg/ml cutpoint, the test was 89 percent specific —
that is, 89 percent of the women without high-grade lesions
or cancer were accurately classified as negative.
At cutpoints above 1 pg/ml, HPV testing was less sensitive –
it did not detect as many of the high-grade lesions. At lower
cutpoints it was sensitive but not specific in this group of
women – it identified as positive many women without high-grade
lesions.
The investigators conclude that the cutpoint of 1.0 yielded
an optimal trade-off between high sensitivity and reasonable
specificity in this population. Compared to conventional Pap
testing, in which cervical cells are examined with a microscope,
the HPV test was more sensitive but less specific.
The authors also conclude that HPV testing can be a useful screening
tool. "Our findings suggest that HPV testing is a viable technology
worthy of consideration in cervical cancer prevention programs,"
said Mark Schiffman, M.D., an epidemiologist at the NCI and
the study's principal investigator.
However, the authors also caution that the usefulness of HPV
testing will vary according to the population being screened
and other factors, such as prevalence of other screening methods
and cost. "Decisions on optimal methods of screening will probably
have to be made on a regional or national basis and depend on
health economic analyses," Schiffman said.
*HPV DNA Testing in Cervical Cancer Screening: Results from Women
in a High-Risk Province of Costa Rica. M. Schiffman, R. Herrero,
A. Hildesheim, M.E. Sherman, M. Bratti, S. Wacholder, M. Alfaro,
M. Hutchinson, J. Morales, M.D. Greenberg, A.T. Lorincs, JAMA,
Vol. 283: 87-93, Jan. 5, 2000.
**Digene Corporation, Gaithersburg, Md.
National
Institutes of Health
Tuesday,
January 4, 2000
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