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Looking for the HPV virus is a far more effective means of detecting cervical cancer in its early stages than the traditional Pap test, according to new Canadian research.

The study, published Thursday in the New England Journal of Medicine, shows the test for human papillomavirus detected 95 per cent of cases in which women had precancerous changes to their cervix, compared with a 55 per cent detection rate with the Pap test.

“Testing for HPV, the virus that causes cervical cancer, is a much better way to screen for cervical cancer than using the Pap test,” said Eduardo Franco, director of the division of cancer epidemiology at McGill University and senior author of the research.

The bad news for women is that the means of collecting samples – scraping cells off the surface of the cervix with a small paddle during a gynecological exam – remains the same. Only the method of laboratory testing is different.

“Unfortunately, the procedure is as unpleasant and embarrassing as ever,” said Pierre Tellier, director of student health services at McGill University. “From a woman's point of view, there is no practical difference.”

The Papanicolaou (Pap for short) test requires a laboratory technician to spot abnormalities in cell samples under a microscope. The HPV test is an automated procedure that detects the DNA of high-risk strains of HPV.

Dr. Franco noted that the detection rate using a Pap test is “only a tad better than flipping a coin.” The test generates a lot of false negatives – meaning it misses some cases of cancer.

The HPV test, on the other hand, generates some false positives, meaning it might suggest cancer when there is none. The HPV test gave a false reading 6 per cent of the time, compared with only 3 per cent for the Pap test.

Dr. Franco said that, based on the research, he would like to see women screened for cervical cancer using the HPV test and, when the virus is detected, there is a follow-up test to look for cellular changes as is now done with a Pap test.

“This would be a reversal of our current approach,” he said.

Currently, screening for cervical cancer is done using the Pap test and, only when the results are unclear, is the HPV DNA test used. Another test, a colposcopy, is required to confirm a cancer diagnosis.

A Pap test costs about $25, while an HPV test costs about $90. In most cases, only the Pap test is covered under medicare; the HPV test must be paid out-of-pocket.

Joan Murphy, head of the divisions of gynecology and gynecologic oncology at The University Health Network in Toronto, said the new study is “tremendously important” and she hopes it will prompt provincial health plans to offer HPV testing at no cost. Mass testing could bring the cost down to as little as $5.

“This study shows us that an HPV test is much more reliable at picking up disease when it exists and, even more importantly, it's better at eliminating the risk of disease,” Dr. Murphy said.

She stressed, however, that the HPV test should not replace the Pap test, but said having both available will ensure women get the correct diagnosis more quickly and efficiently.

The new research involved 10,154 women aged 30 to 69 who went for routine screening at clinics in Montreal and St. John's. All women in the study underwent both HPV and Pap testing, and the results were compared.

A second study, also published in Thursday's New England Journal of Medicine, found that doing both tests increased the cervical cancer detection rate by 51 per cent. Conducted in Sweden, the research involved 12,527 women in their 30s.

If women undergo both tests, they need to be tested only once every three years instead of annually, which could make the approach cost-effective, researchers suggested.

HPV has been in the news a lot of late because there is now a vaccine available to protect against infection with four strains of HPV which, between them, cause about 70 per cent of all cervical cancers. The vaccine, sold under the brand name Gardasil, is recommended for girls and women aged nine to 26; it is being offered, free of charge, in a number of provinces, to girls aged nine to 13.

Dr. Tellier said that, despite the advent of the vaccine, it is important for women to undergo an annual gynecological exam. That is because there are strains of HPV that the vaccine cannot prevent.

About 1,350 women will be diagnosed with cervical cancer in 2007, and an estimated 390 will die of the disease, according to the Canadian Cancer Society.

In addition to cervical cancer, HPV can cause cancer of the mouth and throat, penile cancer, and cancer of the vulva and the vagina.