July 3, 2018 -- Tests that look for the human papillomavirus, or HPV, are more accurate than traditional Pap tests at detecting the precancerous lesions that lead to cervical cancer, according to a Canadian study of more than 19,000 women.
The study finds two key advantages to the HPV test, says Gina Ogilvie, MD, a professor of public health at the University of British Columbia, Vancouver.
"It detects the precancerous lesions that we treat, and it detects them earlier," says Ogilvie, who led the study, published in JAMA.
The other advantage is a need for testing less often. "With a negative HPV, we know testing can be done much less frequently," Ogilvie says. "Women who have a negative HPV test are significantly less likely to have a precancerous lesion 4 years down the road than those who had a negative Pap."
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. Most sexually active adults contract HPV at some point, but it is usually cleared without problems.
Leslie Massad, MD, a professor of obstetrics and gynecology at Washington University in St. Louis, wrote an editorial to accompany the study and agrees with its conclusion that HPV tests perform better than Pap tests. "Since it's a better test at about the same cost and can be done less often, it should replace Pap testing," he says.
Ogilvie's team assigned 19,009 women, average age 45, to HPV testing or Pap testing to find out which test best detected a precancerous lesion known as CIN3. Women in the HPV test group with negative results returned in 48 months. Those in the Pap group with negative results returned in 24 months for another Pap test. At the 48-month mark, both groups got both the HPV test and the Pap test.
Those who had a negative HPV test at the start of the study were less likely to have abnormal cervical cells at the 48-month mark than those who had a negative Pap test at the start. While 2.3 of every 1,000 women in the HPV test group had precancerous lesions at the 48-month mark, 5.5 of every 1,000 women in the Pap test group did.
The study found that primary HPV testing was better at finding precancerous lesions in the first round of testing and more accurately detected them 4 years later.
The Pap test looks for cell changes on the cervix that could progress to cervical cancer. The HPV test looks for HPV, the virus that can cause those cell changes.
Perspective from the American Cancer Society
As more data find the HPV test effective, ''the winds seem to be blowing toward HPV testing alone for women 30 to 65, with cytology [Pap tests] for those under 30," says Otis Brawley, MD, chief medical and scientific officer for the American Cancer Society. He reviewed the study but was not involved in it.
The Cancer Society doesn't suggest HPV testing at this time for women under 30 because the virus is so common in this age group and it generally clears on its own. But if a woman under 30 has an abnormal Pap, her doctor may order an HPV test.
The study also shows that the Pap test was less likely over the 4-year study period to catch signs of severe cervical abnormalities that can progress to cancer, Brawley says.
Testing Recommendations, Current and Pending
"Right now, no [U.S.] organization recommends HPV testing alone," Brawley says.
Under current Cancer Society guidelines, women are advised to get a Pap test every 3 years, ''and if women want a pap and HPV every 5 years that's fine.”
But at 65, women who have had 10 years of ”normal” tests, meaning three Pap smears done every 3 years or Pap and HPV tests every 5, can generally stop testing, Brawley says.
The U.S. Preventive Services Task Force, which also issues screening guidelines, is considering a recommendation for standalone HPV testing. Under the suggested update, under discussion now, women ages 21 to 29 would be advised to have a Pap test alone every 3 years. Women 30 to 65 could choose to have Pap tests every 3 years or HPV tests every 5 years.
Even so, Massad says, he suspects many doctors have not even started to do co-testing with both the HPV and the Pap. "Transitioning to HPV testing alone will take the next decade or longer," he says.
In the future, HPV disease is expected to decline, as more and more young people get the HPV vaccination, Massad says.