September 23, 2014
mother and daughter embracing

Is the Pap Test Passé?

by Berkeley Wellness  |  

For decades women have gone to their gynecologists to get Pap tests as part of their routine exams. Named for Dr. George Papanicolaou, who developed it in the late 1920s, the test involves gently collecting cells from the surface of the cervix and examining them under a microscope to identify precancerous lesions and early (more curable) cervical cancer. It has saved millions of women’s lives worldwide.

But might the routine Pap become a thing of the past? In April the FDA approved the first HPV (human papillomavirus) test, from Roche Pharmaceuticals, that can be used as a primary screening test. Called the Cobas HPV test, it analyzes a sample of cells from the cervix (collected in the same way as for a Pap test) for the presence of any of 14 HPV genotypes that increase the risk of cervical cancer. Before the FDA approval, HPV testing was done only in conjunction with the Pap test, not in place of it.

Nearly all cervical cancers are caused by HPV, with two types responsible for the majority of them. If a woman tests positive for either of these on the HPV test, it’s recommended that she then have an additional test called a colposcopy, in which a special magnifying lens is used to directly examine the cervix (this may also be done following an abnormal Pap test). If a woman tests positive for any of the 12 other high-risk HPV types, she should have a Pap test, which would then determine if she needs a colposcopy. In either case, a positive HPV test does not mean a woman has cervical cancer, but rather only that she is at elevated risk for it.

The ABCs of HPV

There are many different types of human papillomavirus (HPV). Some are associated with genital warts in men and women but the high-risk types are responsible for genital and oral cancers. that are sexually transmitted.

Safe and effective?

Numerous studies have demonstrated that HPV testing is more sensitive than cytology (Pap) testing. One study, funded by Roche and published in the American Journal of Clinical Pathology in 2011, included more than 47,000 women who had Pap and HPV tests; those who tested positive on either then had biopsies to confirm the accuracy of the tests. It found that the HPV test was better than the Pap test in detecting precancerous cells and reducing the rate of invasive cervical cancer. For example, women with negative HPV results had a lower risk of developing more severe cervical cell changes over the next three years than those with negative Pap results.

Another study, in the Lancet earlier this year, combined data from four large trials with more than 176,000 women ranging in age from 20 to 64. It similarly concluded that HPV screening leads to better detection of—and thus better protection against—cervical cancer. An advantage of the HPV test is that the results are fully automated (that is, machine-read); in contrast, the Pap test relies to varying degrees on the expertise of medical personnel to detect cell abnormalities.

But the FDA’s decision is controversial. A coalition of 17 groups—including Consumers Union, the National Organization for Women, and the American Public Health Association—oppose the test as a stand-alone screening tool because they think its safety and effectiveness have not been sufficiently tested and that it will cause more confusion for women and their doctors. Among the concerns, it could lead to overtesting and overtreatment with more invasive procedures (including more colposcopies and biopsies), especially in younger women, who are more likely to test positive for HPV but are at low risk for cervical cancer. Such procedures can have unwanted side effects, including problems with future pregnancy and delivery.

And what about a woman who persistently tests positive for the highest-risk HPV types but then has negative results on colposcopy? She would undergo years of extra surveillance with extra procedures and extra costs—and extra worry.

Though in most cases it would be covered by insurance, HPV testing is also about twice as expensive as a Pap test.

An Anti-Cancer Vaccine

The best way to prevent cervical cancer is to get the HPV vaccine, which is recommended for girls and women ages 11 to 26. It also reduces the risk of other HPV-related cancers including anal and oral cancers.

Ready for prime time?

Whatever the debate, doctors are not likely to start using the HPV test as a primary screening tool soon anyway—at least not in this country. FDA approval was just the first step. The U.S. Preventive Services Task Force, a panel of independent experts that develops screening guidelines for the government, has yet to weigh in. And other health organizations are still mulling it over before they consider changing their screening recommendations. In contrast, the Netherlands, Sweden, Denmark, and parts of Italy have announced plans to use or are considering using the HPV test in place of Pap screening. The test is likely to be especially useful for primary screening in the developing world.

In the meantime, still in effect in the U.S. are the guidelines updated in 2012 by the Task Force, which parallel those from the American Cancer Society (ACS), the American Society for Clinical Pathology (ASCP), and the American Society for Colposcopy and Cervical Pathology (ASCCP):

  • Women ages 21 to 29 should have a Pap test every three years. Women under 21 should not be screened.
  • Women under 30 should not be screened for HPV.
  • Women ages 30 to 65 should have a Pap test every three years or be “co-tested” with an HPV and Pap test every five years. The latter is “preferred” by ACS, ASCP, and ASCCP.
  • Women over 65 should stop routine screening if they’ve had normal results in recent years and are not at increased risk, as should women who have had a hysterectomy with removal of the cervix for reasons other than cancer.

Keep in mind: Annual screening is not recommended for any women as it had been in the past, because it’s now recognized that this offers little if any extra benefit and increases potential harms. Still, more frequent screening (more often than every three or five years) is recommended for women who have abnormal results, or may be advised for those who smoke, have multiple sex partners, are immunocompromised, or are otherwise at higher risk for cervical cancer.

Bottom line: Unlike most cancers, there are excellent screening tests for cervical cancer. What’s most important is to be screened, period, whichever protocol you follow. The current guidelines are reasonable for most women, but talk to your health care provider about which screening option is best for you. It will depend on your age, previous test results, medical history, and personal preferences.

If an HPV test is recommended, it won’t feel different from having a Pap test (the two tests are typically done at the same time). In fact, if you’re a woman 30 or older, there’s a good chance you’ve already had HPV testing, even if you didn’t know it. The CDC provides a good resource on how to make sense of Pap and HPV test results.