HPV test better than Pap when screening for cervical cancer

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A study from Canada found that an initial test for human papilloma virus (HPV), which causes nearly all cases of cervical cancer, led to the discovery of more pre-cancerous lesions than were found with conventional smear tests.

One of these methods is co-testing for the human papillomavirus (HPV), which causes 99 percent of cervical cancer. One group got the HPV test to screen for cervical cancer, almost all cases of which are caused by HPV, the most common sexually transmitted infection.

The HPV test also seemed better at predicting who'd stay cancer-free, the investigators found. Women whose HPV test showed they didn't have the infection were less apt to develop a pre-cancerous lesion over the next four years, compared to women who'd gotten the Pap test alone.

A visit to the gynecologist for cervical cancer test is often an unpleasant necessity for women under 65. Women also filled out questionnaires about lifestyle and sexual health history to ensure differences in results were not down to imbalances between the test groups.

Of note, the Canadian Task Force on Preventative Health Care differs from the USA task force - it recommends Pap smear screening every three years between ages 30 and 69, citing weak evidence for screening women ages 25 to 29.

The women who took part in the study were aged between 25 and 65, had not had a smear test in the past 12 months, were not pregnant, and had no history of cervical cancer or pre-cancerous changes in the past 5 years.

According to Dr. Kathleen Schmeler, who is a gynecologic oncologist at the University of Texas MD Anderson Cancer Center, the findings of this study have great implications on women's health. He said that although the study confirmed previous research showing that the HPV test is more sensitive than the Pap test, it didn't answer a critical question: Is the HPV test alone better than the HPV test and the Pap smear together, as is current practice? Also, there are various HPV DNA tests available globally, where a lot of them are FDA approved for detecting high risk HPVs.

But four years later, the referral rates were 49.2 per cent in the HPV group compared with 70.5 percent in the other, suggesting earlier detection of the virus.

"These results have demonstrated that primary HPV testing detects cervical neoplasia earlier and more accurately than cytology", they wrote.

'Research shows HPV primary screening will save an estimated 400 cervical cancer diagnoses every year so any delays to roll out could result in diagnoses which could have been prevented. But one issue is that it was centered around one ideal system in British Columbia, where they had one place to send all of the Pap smears and HPV testing. He cites the small group of women who had abnormal cells discovered through a Pap smear at the end of the study period.

But HPV testing is thought to have a lower specificity for CIN2+ than cytology screening, which could result in more colposcopies and biopsies being performed - some of which may be unnecessary, says the author of a related but separate JAMA editorial.

Almost all cases of cervical cancer are caused by persistent infections of high-risk HPV, which causes changes to cervical cells. The final round of co-testing found additional abnormal cells in some women who originally tested negative in both groups. About 4,200 women will die of the disease. They focused mainly on moderate or severe changes to cervical cells (pre-cancerous changes) that could lead to cervical cancer. Where it is hard to apply HPV tests over pap smear for USA as there hasn't been head to head comparison until now.

Its replacement? The human papillomavirus test. Partly because of that, he said, "we're a long way away from replacing the Pap smear".

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