Traditional Pap Test Inferior To HPV Test

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Main Category: Cervical Cancer / HPV Vaccine
Also Included In: Women's Health / Gynecology
Article Date: 18 Oct 2007 - 0:00 PDT

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Researchers at McGill University have revealed that the HPV screening test is superior to the traditional Pap test in detecting cervical cancer. Accuracy for the HPV test was 94.6%, compared to 55.4% for the Pap test, say researchers.

Dr. Marie-Hélène Mayrand, Centre hospitalier de l'Université de Montréal (CHUM), and team from McGill, Université de Montréal, the Newfoundland and Labrador Public Health Laboratory and McMaster University, published their findings in The New England Journal of Medicine, October 18th issue.

The controlled randomized trial, called CCCast, was the first of its kind carried out in North America for HPV testing as a stand-alone screening test for cervical cancer. Initially, it involved 10,154 women during the period 2002-2005 - they were aged 30-69 years.

Although HPV tests were 40% more accurate than Pap tests, as far as the specifity scale was concerned, the Pap test faired better. Pap tests' ability to accurately detect pre-cancerous lesions without false positives was better - 96.8% compared to 94.1%.

The researchers explained "We already knew before conducting this study that the sensitivity of Pap left a lot to be desired. However, 55.4% accuracy is only slightly above chance. Flipping a coin gives you 50%."

The Pap test, which was created by Dr. Georgios Papanicolaou during the 1940s, require that cell samples are gathered from the patients cervix and examined under a microscope by technicians. This procedure has been the norm for more than half a century. The HPV test, on the other hand, although requiring cervical samples, is analyzed automatically - it detects the DNA of HPV strains which are known to cause cervical cancer.

A test's sensitivity is generally thought of as more useful than specifity. Event though a false positive is psychologically distressing, the patient is free of the disease, explain the researchers.

Even though the results of this study may have some relevance regarding the current debate about HPV vaccinations on young females, the issues should be looked at separately, say the scientists. Vaccination is all about primary prevention (screening), while this study focuses on secondary prevention, the researchers stress.

Women who receive the vaccine will still have to be screened because their vaccine only protects them against 70% of cervical cancers.

Read the article at McGill University web site

Written by: Christian Nordqvist
Copyright: Medical News Today
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