NEJM Report Finds HPV Test More Effective Than Pap in Determining Cervical Cancer Risk
Gaithersburg, MD (USA), and Hilden, Germany - Oct. 18, 2007 - The first randomized, controlled study in North America of HPV testing as a stand-alone screen concluded that it is almost 40 percent more accurate than traditional cytology (the Pap "smear") in identifying women with advanced cervical disease, according to a report published today in The New England Journal of Medicine.
The study, which involved more than 10,000 Canadian women age 30-69, found that the HPV test's sensitivity - its ability to accurately identify women with pre-cancerous cervical cells or cancer - was 94.6 percent, compared to 55.4 percent for the Pap. HPV (humanpapilloma virus) is the primary cause of cervical cancer.
This seminal study used QIAGEN's Hybrid Capture® 2 High-Risk HPV DNA test -- the only such test that is both CE-marked in Europe and approved by the U.S. Food and Drug Administration1. The molecular diagnostic test was developed by Digene Corp., now part of QIAGEN N.V. (NASDAQ: QGEN; Frankfurt, Prime Standard: QIA). The performance of QIAGEN's HPV test has been validated in studies that included more than 300,000 women.
"We already knew before conducting this study that the sensitivity of the Pap left a lot to be desired," stated one of the study's authors, Eduardo Franco, DrPH, of Montreal's McGill University, in a news announcement. "However, 55.4 percent accuracy is only slightly above chance. Flipping a coin gives you 50 percent."
Participants in the Canadian Cervical Cancer Screening Trial (CCCaST) were randomly assigned to a "focus on Pap" or "focus on HPV" screening group, although for ethical reasons, both groups received both tests. In this study, conventional cytology was used. Recent analyses have found that the newer "liquid-based" cytology does not significantly improve the ability to detect disease. All CCCaST participants who tested positive on either the Pap or HPV test were referred for a follow-up biopsy. In addition to the HPV test's greater sensitivity, the study found that its specificity - the likelihood that women with positive results actually have disease - was only slightly less than the Pap's (94.1 percent vs. 96.8 percent).
HPV testing for routine cervical cancer prevention is currently most widely practiced in the United States, where it is approved for use along with a Pap in women age 30 and over. Under the currently recommended guidelines, screening that includes HPV testing may be performed at longer intervals than when the Pap is used alone. However, the authors of the NEJM report concluded that co-testing "only marginally improved sensitivity compared with HPV testing alone".
The conclusions of CCCaST reinforce a growing number of other studies showing greater sensitivity for HPV testing and suggesting its use as the primary, front-line screen -- with the Pap reserved for follow-up evaluation.2 For example, most recently, the Oct. 4 issue of The Lancet reported on a trial involving more than 17,000 women in the Netherlands. The study, led by Professor Chris Meijer of VU Medical Centre in Amsterdam, concluded that HPV DNA testing detects pre-cancerous cervical cells earlier than the traditional Pap, thus allowing longer intervals between screenings. This is an important feature for health authorities working to control costs - particularly those in developing countries, where a variety of obstacles make it difficult for women to access regular medical care.
Medical experts agree that the most effective approach to cervical cancer prevention combines HPV vaccines for girls and young women with screening of older women.
"We believe that a shift from cellular to viral (screening) tests, coupled with education and vaccination, will contribute to more efficient control of cervical cancer," the authors stated in the NEJM report.
About HPV and cervical cancer
Worldwide, cervical cancer affects more than 400,000 women annually and, after breast cancer, is the second-most-common malignancy found in women. Cervical cancer is caused by "high-risk" types of the human papillomavirus (HPV), which are sexually transmitted. It's estimated that 80 percent of women will get an HPV infection at some point in their lives. However, in most cases, the infection goes away or is suppressed by the body without causing problems. It is only infections that persist that can cause abnormal cells to form that may develop into cervical cancer if not detected and treated early.
QIAGEN N.V., a Netherlands holding company, is the leading provider of innovative sample and assay technologies and products. QIAGEN's products are considered standards in areas such as pre-analytical sample preparation and assay solutions for life sciences, applied testing and molecular diagnostics. QIAGEN has developed a comprehensive portfolio of more than 500 proprietary, consumable products and automated solutions. The company's products are sold to academic research markets, leading pharmaceutical and biotechnology companies, applied testing customers (such as in forensics, veterinary, biodefense and industrial applications) and molecular diagnostics laboratories. QIAGEN products are sold through a dedicated sales force and a global network of distributors in more than 40 countries; the company employs more than 2,600 people worldwide. Further information about QIAGEN can be found at http://www.qiagen.com/. Further information about HPV DNA testing can be found at http://www.thehpvtest.com/.
1The hc2 High Risk HPV test has been approved by the Food and Drug Administration for the follow-up evaluation of women with ASC-US (inconclusive) cytology and for use as an adjunctive test combined with the Pap to screen women age 30 years and older.
2This information is provided as a summary of several clinical studies. The use of the Hybrid Capture® High-Risk HPV DNA Test as a stand-alone screen for cervical cancer has not been approved by the U.S. Food and Drug Administration.