Test for virus that causes cervical cancer should replace Pap, FDA advisors say

FDA committee advises replacing Pap with DNA test for human papillomavirus

When Dr. George Papanicolaou started developing the Pap test in the 1920s, he didn’t know what caused cervical cancer – he just wanted to detect it at the earliest possible stage. His test became one of the biggest success stories in cancer screening, with cervical cancer death rates declining by almost 70 percent between 1955 and 1992. Now a federal advisory committee has recommended that the FDA approve a DNA test that could be even more effective than the Pap test – and could save even more women’s lives.

The test detects the DNA of human papillomavirus, or HPV, which causes the vast majority of cervical cancer cases. It builds on breakthroughs made at Fred Hutchinson Cancer Research Center, where Drs. Denise Galloway and Janet Daling first used DNA tests to show that HPV causes a variety of cancers. Galloway and Dr. Laura Koutsky, of the University of Washington, also helped lay the foundation for an HPV vaccine that has prevented cervical cancer in hundreds of thousands of women worldwide.

“In just 25 years, we went from not having any idea what viruses were involved in these cancers to having a vaccine,” Galloway said in an earlier interview. “That’s amazingly fast.”

A better way to detect cervical cancer
The American Cancer Society estimates that about 12,360 women will be diagnosed with cervical cancer this year. Current guidelines call for women between the ages of 21 and 65 to undergo a Pap test every three years. Women between age 30 and 65 can extend that interval if they undergo both Pap and HPV tests every five years. Women younger than 21 and over 65 should not be tested.  

The new recommendation calls for the FDA to approve an HPV test developed by Roche Holding AG as a primary test, which means it could be given instead of the Pap test. The test detects two types of HPV that account for approximately 70 percent of all cervical cancer cases. According to a New York Times report, Roche study showed the DNA test was more effective than Pap testing at signaling whether a woman had precancerous lesions. The same study found that if the DNA test came back negative, it was better than the Pap test at predicting whether a woman would develop lesions within three years.

It could be years before the DNA test is incorporated into standard practice. If the FDA accepts the panel’s recommendation, medical associations must follow suit and incorporate it into the guidelines that doctors follow. Some opponents argue that the new test might not make much difference. They say cervical cancer strikes women who’ve never been tested for the disease, not women whose cancer was missed during Pap screening. It also isn’t yet clear if the DNA test alone would be better than the current combined Pap and DNA testing.

Preventing cervical cancer worldwide
Still, the recommendation signals another step in the push to save women from cervical cancer by improving how HPV is detected and prevented. Galloway and her colleagues have been leaders in this effort for more than two decades. Their research helped show HPV vaccines were possible, and Galloway’s lab played a role in clinical trials that proved the vaccines were effective.

In June, the Centers for Disease Control and Prevention announced that since the HPV vaccine was introduced in 2006, HPV rates have dropped 56 percent in girls between the ages of 14 and 19.

This could be just the beginning, as young girls in developing countries will soon have better access to the vaccine. Last summer, the makers of two key vaccines, Gardasil and Cervarix, agreed to lower the price from $300 for three doses to just $5 per dose.

Now Galloway’s team is researching ways to modify vaccine strategies.

“We’re hoping to extend vaccine coverage to more women,” says Dr. Erin Scherer, a research associate in Galloway’s lab.

They’re also working to identify whether viruses contribute to other cancers – and whether they can be prevented by vaccines.

In addition to HPV, “If we find even one virus that is associated with one type of cancer, it will make a huge difference,” Galloway said.

Solid tumors, such as cervical cancer, are the focus of Solid Tumor Translational Research, a network comprised of Fred Hutchinson Cancer Research Center, UW Medicine, and Seattle Cancer Care Alliance. STTR is bridging laboratory sciences and patient care to provide the most precise treatment options for patients with solid tumor cancers. 

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Justin Matlick is a writer and editor at Fred Hutchinson Cancer Research Center. He started his career at the Wall Street Journal and has written for a variety of national publications. Reach him at Jmatlick@fredhutch.org.

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