New Test for Cervical Cancer Allows Women to Gather Tissue Samples Themselves
Wright and colleagues examined 1,415 previously unscreened women aged 35-65 from a township outside Cape Town, South Africa. Women self-performed a vaginal swab with the special collection kit at a clinic and, after returning it, were then screened using a conventional Pap test, visual inspection of the cervix, and HPV testing of a physician-obtained vaginal sample.
The physician-performed HPV DNA test was positive in 84% of women with precancers and cancers, whereas the conventional Pap smear was positive in 68%. In the patient-collected samples, HPV was positive in 66%. The false-positive rates -- the percentage of cases diagnosed incorrectly as cancer or precancer -- were 17% for HPV testing of self-collected samples and 12% for Pap smears.
"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.