Rapid Test for Cervical Cancer Virus Aimed at Developing Countries

Cervical cancer is the second most common cancer in women, striking nearly 500,000 women worldwide and killing almost 300,000 each year. The majority of cases of cervical cancer and cervical intraepithelial lesions (considered a precursor to cancer) are associated with infection with certain strains of human papilloma virus (HPV), a virus that also causes warts. There are two types of tests that are often used to screen for cervical cancer and its precursors – Pap smears and tests to detect HPV. Use of liquid cytology Pap smears—a screening test that requires examining patient samples under a microscope— has reduced mortality rates 50-70% in the U.S., Canada, and Europe, but developing countries lack the appropriate infrastructure for using this method and newer, more accurate strategies that detect HPV DNA.

A simple, experimental (not currently available in the U.S.) test that rapidly (within three hours) detects several types of HPV that can cause cervical cancer has been developed. This relatively rapid test could help developing countries improve screening and detection of cervical cancer. The test, called careHPV, doesn’t require specially trained personnel, much bench-top workspace, or a sophisticated lab infrastructure. The test was developed through collaboration between a diagnostics company and an international nonprofit organization dedicated to public health, with funding from the Bill and Melinda Gates Foundation. Because of its simplicity and rapid completion, it potentially allows screening and clinical follow-up to be completed on the same day.

A study published in Lancet Oncology in October 2008 compared this new test to other screening tests. A team of researchers from China, the United States, Canada, and Great Britain involved more than 2,500 women ages 30 to 45 at two hospitals in Shanxi Province, China. Using both vaginal specimens collected by patients and cervical specimens collected by clinicians, the researchers compared careHPV’s performance with other screening tests, including visual inspection of the cervix with acetic acid (VIA), another DNA test designed for developed countries, and liquid-based cytology.

Among 2388 women with complete data, almost 3% had precursors of cervical cancer. The careHPV correctly detected these changes in cervical cells 90% of the time and correctly excluded samples without abnormal changes 84.2% of the time. On vaginal samples, careHPV correctly detected these changes 81.4% of the time and excluded samples without such changes 82.4% of the time. For liquid cytology on cervical samples, these figures were 85.3% and 97.0%. Another DNA test for cervical cancer more suited to environments with more resources correctly detected these changes 97.1% of the time and correctly excluded them 85.6% of the time on cervical samples.

“Overall, careHPV seems to have performance characteristics that merit further study and, subject to local cost-effectiveness assessments, might be appropriate for use in resource-constrained screening programmes,” the researchers write.

An accompanying commentary in the same journal states that the results are encouraging but calls for more study of careHPV before implementing its widespread use. “The ability to obtain accurate results in a few hours is especially important in settings where women are screened only occasionally, allowing for treatment of high-grade [precursor] lesions at the same visit. After many years of research, the emergence of a simple, fast HPV-DNA test with the potential to become an objective and reliable tool for cervical-cancer screening is exciting to see” writes the commentator.

The commentary also called for examination of more comprehensive HPV screening tests as HPV vaccines become available in more countries, including surveillance of cervical cancer incidence among both vaccinated and non-vaccinated women. A new World Health Organization program, LabNet, is establishing a global HPV laboratory network that adheres to standard quality practices so this surveillance is accurate. Ultimately, LabNet can help assure the best HPV test performance in different settings.

Sources

Qiao, Y. et al. A New HPV Test for Cervical-Cancer Screening in Developing Regions: A Cross-Sectional Study of Clinical Accuracy in Rural China. The Lancet Oncology 2008; 9: 929-936.

Villa, L. Assessment of New Technologies for Cervical Cancer Screening. The Lancet Oncology 2008; 9: 910-911.

Wald, A. Cervical Cancer Screening Test Tailored for Use in Developing Countries. Journal Watch Women's Health. October 30, 2008. Available online at http://womens-health.jwatch.org/cgi/content/full/2008/1030/4?q=etoc_jwwomen. Accessed November 2008.

Tests: HPV, Pap smear
Conditions: Cervical cancer