Mar 21, 2014 7:40 PM
March 21, 2014 -- Is the Pap test going the way of car phones and Walkmans?
Pap tests are used to find early signs of cervical cancer. But over the past several years, studies from a number of countries have found that HPV tests are better than the Pap test at finding cervical cancer.
While HPV tests have been on the market for more than a decade, they are approved only for use along with the Pap test.
Earlier this month, an FDA advisory panel unanimously recommended that the FDA approve the HPV test made by the pharmaceutical company Roche as a first one to use for cervical cancer screening tests. The FDA often agrees with advisory panel recommendations, but it doesn't have to.
Current cervical cancer screening guidelines, set by major organizations, say to test women every 3 years from age 21 to 65 with a Pap smear, or every 5 years from 30 to 65 with both a Pap test and an HPV test.
WebMD asked Debbie Saslow, PhD, director of breast and gynecologic cancer at the American Cancer Society, and Alan Waxman, MD, professor of obstetrics and gynecology at the University of New Mexico and a member of the FDA advisory panel, to help sort out the questions that remain.
HPV is short for human papilloma virus, which can be spread through skin-to-skin contact. Certain types of HPV cause nearly all cervical cancers -- these are called "high risk" types. Other types of HPV cause genital warts.
After doctors began testing women with the Pap test in the 1940s, new cases of cervical cancer and deaths from it dropped dramatically. But the drop in cases has leveled off in recent years, particularly in women under 50.
The American Cancer Society estimates that in 2014, 12,360 U.S. women will be diagnosed with cervical cancer and 4,020 will die of it.
The FDA first approved Roche's HPV test in April 2011 for women ages 21 to 29 who have an abnormal Pap test, and as a "co-test" with the Pap test for women ages 30 to 65. The test is designed to find DNA from HPV 16 and HPV 18, the two types of HPV that cause 70% of cervical cancer cases worldwide. It also checks for DNA from 12 other high-risk types of HPV.
Roche's HPV test is not the only one. Other tests look for other combinations of high-risk HPV types.
About half of women 30 and older who get a Pap test also get an HPV test, Saslow says. Not all doctors give both tests.
"New technologies and new protocols take a while to catch on," Waxman says. If the FDA approves Roche's HPV test as a primary test, he says, "my guess is ... it's going to take a long time before we see a major shift in the way women are getting screened."
Women who do get both tests might not realize it, because samples for the two tests are collected from the cervix at the same time.
While cervical cancer screening guidelines recommend that only women 30 and older get an HPV test, Roche proposes that its test be used in women as young as 25.
Their study followed women age 25 and older for 3 years. They received HPV and pap tests each year.
Saslow cautions it's not clear whether women could go longer than 3 years that between normal HPV tests. Under current guidelines, women age 30 to 65 who get both tests can go 5 years between tests.
For the past 6 months, Saslow and representatives of other organizations involved in cervical cancer screening tests have been working on "interim guidance" for doctors and patients. They plan to have their guidelines ready by the time the FDA makes a decision.
Roche provided confidential research information to the group before it was made public at the FDA meeting, Saslow says. To help fill in the blanks, the working group is also looking at research done in Canada and Sweden and by Kaiser Permanente in Northern California.
That depends. According to Roche's application to the FDA, women whose tests show HPV 16 or 18, the highest-risk types, would then get a more thorough test called a colposcopy.
Women whose tests don't show HPV 16 or 18 but do show one of the other high-risk HPV types would have a Pap test. If their Pap test is not normal, they would get a colposcopy.