HPV test better than Pap smear at detecting cancerous cervical changes

Henrietta Strickland
July 5, 2018

Still, it seems that more accurate outcome came from the HPV test than from the Pap smear, which could influence decisions in the future.

Ever since Georgios Papanicolaou developed his eponymous cervical smear in the 1940s, Papanicolaou (Pap) testing for cervical cytology is one of the most widely used cancer control interventions in the USA. Generally speaking, women who had the Pap smear were more than twice as likely to have abnormal cells; HPV testing resulted in 22 cases whereas the Pap smear had 52 women with abnormal cells.

"What our study shows is that by using HPV testing, we detect precancerous lesions earlier", says lead author Dr. Gina Ogilvie.

Numerous medical groups have said that before moving to HPV testing only, they needed to see clinical trial results - such as the kind provided by the new head-to-head study - to determine which test, over time, was better at detecting the precancerous changes.

In 2018, the American Cancer Society expects more than 13,000 new cases of cervical cancer and more than 4,000 deaths from it. HPV causes the vast majority of cervical cancers, experts agree.

Pap smears rely on the human eye to get results, says Dr. Diane Harper, a professor of medicine who researches HPV at the University of MI, "and it's far preferable to detect problems on a molecular level". Infection with HPV types targeted by the vaccine has declined by almost two-thirds among teenage girls since HPV vaccination was recommended in the United States, according to a study that also found that there was a decrease in HPV infections among women 20 to 24. The Pap smear has been around for 50 years, so co-testing remains a viable option, Wright said.

Although there could be increased costs associated with sending more patients for additional tests and monitoring after HPV detection, those may be offset by the fact that people may not need to have the initial screening as often, she said.

"But we will gradually move to more HPV testing for primary screening", he said. Pap smear and HPV testing market can be classified into five major segments, namely, monoclonal and polyclonal antibodies, immunoassays, molecular diagnostics, chromosomal analysis, and other analyses.

Schmeler often works in Latin America where, in countries like El Salvador, cervical cancer is one of the most common cancers in women primarily due to poor screening programs. Two years later, the ones that tested negative after the Pap smear had another test of the same type. These HPV viruses are sexually transmitted and can cause most of the anal cancers; many vulvar, vaginal and penile cancers; and some oropharyngeal cancers as well along with the cervical cancers. They recommend further studies to help researchers understand long-term clinical outcomes and cost-effectiveness across both tests.

After four years, the women who got HPV tests were less likely to have serious changes that can lead to cervical cancer, a diagnosis of cervical intraepithelial neoplasia 2 or 3 (CIN2 and CIN3), Ogilvie's team found. But according to the study, cumulative CIN2+ incidence was similar in the two groups after the end of the trial at 72 months.

Women can get a clear result from a simple HPV test and those who receive a negative result will be able to trust those results for several years, she says. Now, armed with the new study and previous ones, some experts say the Pap smear should be dropped. In 2017, the researchers running the study reported that there were significantly more cases of precancerous lesions detected early in the trial among the women in the HPV-tested group, compared with the Pap cytology group. "Even if we could magically vaccinate 100 percent today, it would take 30 years for them to reach the age of 40, and to see a meaningful decrease in cervical cancer", Spitzer added. Both group were tested again using both methods after four years.

"It's really incredible, there's no other test that gives us this level of reassurance for that period of time for a cancer", Harper says.

Human papillomavirus (HPV) is a DNA virus from the papillomavirus family.

Medical students learn how to insert a speculum, part of the process of performing a Pap smear.

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