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Be it Pap tests, HPV tests, or both, cervical cancer screening is important. This article explores screening paradigms and offers a glimpse of what's to come.
The Pap smear, which looks for precancers and cell changes in the cervix, is one of the most successful cancer screening modalities developed. Between 1955 and 1992, it is estimated that the rate of cervical cancer mortality decreased by about 70%, due largely to the widespread adoption of the Pap smear as part of the annual Ob/Gyn or well-woman visit.
The Pap test stood alone as a line of defense against cervical cancer for decades; however within the last twenty or so years, there has been increased understanding of the role of the human papilloma virus (HPV) in the development of cervical cancer. The virus was found to be responsible for almost all cervical cancers, with HPV types 16 and 18 estimated to cause cervical cancer in about 70% of cases. This discovery led to the development of molecular tests to measure the presence of HPV.
As HPV tests emerged and studies continued to evaluate their role in detecting cervical cancers, the health care community has questioned how HPV testing should be incorporated into the well-woman visit and, moving forward, where increased use of HPV testing leaves the Pap test.
The first big change to the well-woman visit came several years ago when the United States Preventive Services Task Force and the American Cancer Society recommended against routine yearly Pap smear testing and first included HPV testing as part of cervical cancer screening.
The new guidelines recommended Pap testing every 3 years for women aged 21 to 65 years. In addition, women aged 35 to 60 years could be screened every 5 years when screened with a combination of Pap smear and HPV testing. Women older than age 65 years who are at low risk can stop cervical cancer screening all together. These recommendations were also presented by the American College of Obstetricians and Gynecologists (ACOG).
Research leading to this change in recommendations indicated a very low likelihood for precancer or cancer developing among women with a negative HPV test. However, women with a positive HPV test had a 5% to 10% chance of the disease developing.
With the health care community only just adjusting to these updated screening recommendations, even more changes may be around the corner. In April, the FDA expanded the label for one of the HPV tests available on the market, the cobas HPV Test (Roche), approving it as a stand-alone test for primary screening of cervical cancer. Using this test, women who test positive for HPV 16 or 18 should undergo follow-up with colposcopy and those who test positive for one of the other 12 types of high-risk HPV types should undergo Pap testing to clarify the need for colposcopy.
The test’s approval was based on the results of the ATHENA study, which evaluated 47,208 women aged 21 years or older. Results of the study indicated that one in four women who tested positive for HPV 16 had cervical cancer within 3 years and that one in seven women who had normal Pap tests but were positive for HPV 16 had high-grade cervical disease missed by cytology alone.
Reaction to the FDA approval and the idea of using HPV testing alone to screen for cervical cancer has been mixed, and whether or not professionals will begin to use the HPV test for first-line screening is unknown.
“There is concern about using HPV testing alone in women between ages 25 and 29 because so many of these women will be HPV positive,” said Edward Evantash, MD, Medical Director and VP of Medical Affairs at Hologic. “Most adults will naturally and spontaneously eliminate the HPV infection and testing for HPV alone in that group may create a great deal of unnecessary anxiety and lead to unnecessary invasive procedures.”
The Society for Gynecologic Oncologists and the American Society for Colposcopy and Cervical Pathology have announced plans to release interim guidelines on cervical cancer screening that will discuss use of the HPV test as a first-line screening method. In addition, the American Cancer Society is reviewing its guidelines and considering this new information.
Until then, though, Dr Evantash said that physicians should follow current recommendations, which suggest co-testing in most women.
“We have had such gains in the prevention of cervical cancer and its precursors, and continue gains as we adopted HPV into our screening paradigm, that dropping one of those tests-the Pap test-seems like a step backwards,” Dr Evantash said. “Until we have more data to fully understand what that loss of sensitivity will be like and how that will impact the cervical cancer rates moving forward, it is alarming that people may be adopting this prematurely.”
Recommendations aside, what is your preferred cervical cancer screening test/schedule for your patients?
(We welcome your answers in the Comment section below.)