March 13, 2014 — An FDA advisory panel on Wednesday unanimously recommended that a human papillomavirus test developed by Roche replace the Pap test as the primary screening tool for cervical cancer, the New York Times reports.
Currently, the HPV test -- which detects the DNA of HPV, which causes nearly all cervical cancer cases -- is used in conjunction with a Pap test or as a follow up when Pap test results are inconclusive.
However, even if FDA takes the advisory panel's advice and approves the new test, the Pap test "will not go away quickly, if at all," according to the Times. Rather, the HPV test would give women's health care providers a new option for cervical cancer screening. Further, the test likely would not be commonly used until professional medical societies recommend it, which could take several years, the Times notes (Pollack, New York Times, 3/12). FDA is not required to follow the recommendations of its advisory panels, but it usually does (Frieden, MedPage Today, 3/12).
Current guidelines recommend that women ages 30 to 65 receive a Pap test alone every three years or have both the Pap test and the HPV test every five years. Women ages 21 to 30 are advised to undergo the Pap test every three years.
According to the American Cancer Society, about 12,360 women in the U.S. will be diagnosed with cervical cancer in 2014, resulting in about 4,020 deaths. The Pap test is credited with helping drop the cervical cancer death rate in the U.S. by about 70% between 1955 and 1992, but it has since leveled off, the Times reports (New York Times, 3/12).
Facts on HPV Test
The HPV test detects HPV genotypes 16 and 18 and about 12 other high-risk strains (MedPage Today, 3/12). Types 16 and 18 account for about 70% of cervical cancer cases, according to the Times. Studies have demonstrated that the HPV test is more sensitive than the Pap test in detecting precancerous lesions. In addition, proponents of the HPV test contend that it is more consistent, noting that lab results from HPV tests tend to vary less frequently than those of Pap tests, which rely on people examining slides under a microscope.
The "main drawback" to the HPV test is that most people become infected with the virus after they become sexually active, even though in most cases their immune system will clear the infection. As a result, many women -- particularly those who are younger -- could be unnecessarily sent for further testing if they initially test positive, which is why current recommendations suggest both tests only for women ages 30 and older.
However, Roche argues that its HPV test addresses those concerns by specifically testing for genotypes 16 and 18. In addition, Roche's study of the test found that a negative HPV test was a better indicator than a Pap test in predicting that a woman would remain free of lesions for at least three years (New York Times, 3/12).
FDA's Medical Devices Advisory Committee Microbiology Panel in a 13-0 vote said that Roche's HPV test is safe and effective and that its benefits outweigh any potential risks.
Specifically, the panel agreed with Roche's proposal to market the HPV test as a first-line cervical cancer screening method. Women ages 25 and older who tested positive for HPV 16 and 18 would then undergo a colposcopy for further assessment, while those who tested negative for HPV 16 and 18 but positive for other high-risk strains would undergo a Pap test to determine the need for a colposcopy. Meanwhile, women with completely negative results would be monitored for follow up at their physicians' discretion.
The panel cited results of Roche's study of the test -- a long-term follow-up involving 47,208 women -- that found the HPV test "detects more women with disease and requires fewer women without disease to go to colposcopy than cytology alone."
Panel Members Note Drawbacks
Panel members also acknowledged some potential shortcomings with the HPV test, including how the study showed that about 11% of women ages 25 to 29 tested positive for HPV 16 and 18, compared with 7.28% of women in the same age range who underwent a Pap test. Panel member Paula Hillard, a physician at Stanford University, said this finding suggests that more women undergoing just the HPV test in that age group "will be anxious about potentially having cancer."
Hillard and panel member Kenneth Noller, of the American Board of Obstetrics and Gynecology, also raised concern about off-label use, noting that the way tests are used in practice often differs from what FDA approves. Hillard said, "I'm concerned that all those women potentially with other high-risk positivity won't go to Paps next but go [straight] to colposcopy. That's not what's proposed here, but what control does FDA have once it's out there?" (MedPage Today, 3/12).