New Test for Cervical Cancer Allows Women to Gather Tissue Samples Themselves
"I'm really excited about these findings that suggest that what we can now do is expand cervical cancer screening to many women in the world who do not routinely undergo gynecologic examinations," says Wright. "I think that the combination of showing that HPV DNA testing using a clinician-taken sample is more sensitive for cervical cancer than a conventional Pap smear, as well as our finding that the patient-taken sample is as sensitive as a regular Pap smear, really opens the door to changing the way we screen for cervical cancer both in the United States and abroad."
The second study, conducted in Costa Rica by the National Cancer Institute, found that HPV testing detected 70% more cervical disease than the conventional Pap smear. The 8,554 women were examined by visual inspection of the cervix if they had abnormal findings on either a conventional Pap smear or one of two other Pap smear methods. HPV testing was performed subsequently.
Although HPV is present in almost all cases of cervical cancer, many HPV-positive women do not develop cancer. The researchers found that sensitivity for detecting cervical cancer was much higher with HPV testing than with conventional methods used to determine if cancer is present. But many more women were referred for visual inspection of the cervix secondary to a positive HPV test even though they did not have cancer.
The HPV DNA test used in both studies was the Hybrid Capture test manufactured by Digene Corporation, which provided some research support in both studies. According to Attila T. Lorincz, PhD, a co-author of both studies and scientific director of Digene, HPV testing "takes the guesswork" out of the current approach to cervical cancer screening.
"The HPV test is simple to learn and do on a routine basis," Lorincz says. "It gives the same result again and again. There are no inter-observer problems, as there are with the conventional Pap smear. Thus, the HPV test is well suited for mass screening programs."
In an editorial accompanying the studies, Jack Cuzick, PhD, of the Imperial Cancer Research Fund in London, says that the enhanced sensitivity of the HPV test offers the possibility of being able to screen women less often, and with greater confidence, when used with a conventional Pap smear. Cuzick says that the added possibility of being able to let women do self-collecting of vaginal swabs could have a significant impact on improving the percentage of women who are routinely screened.
Although the HPV test is available for use in the U.S., it is not approved for routine cervical cancer screening. Cuzick says that based on the results of these and other studies showing the value of HPV DNA in detecting cervical cancers, he believes all women over age 35 should have regular HPV testing in addition to a Pap smear, but the exact intervals for that testing are unclear.