Millions of women worldwide have been tested for cervical cancer, human papillomavirus (HPV) and other problems via the Pap test. The procedure was invented in 1943 by Dr. George Papanicolaou (thus the name), and has become the most widely used cancer-screening test in the world. The test involves taking a scraping of the cells from the uterine cervix, and examining them microscopically for any abnormalities that could indicate a precancerous or cancerous condition. Recently, however, an FDA advisory committee has unanimously recommended replacing the venerable Pap test with a new one the cobas test that is specific to HPV, the virus that is the most frequent cause of cervical cancer.
The cobas viral test is already approved as a follow-up procedure for women who have had abnormal Pap tests, and also for use with the Pap test to screen for the high-risk strains of HPV p16 and p18 in women who are 20 to 65 years old as well as 12 other high-risk strains.
Roche, the developer of the cobas test, has now proposed to the FDA that the cobas test be used as a substitute for the Pap test. Based on a prospective cohort study, the test was more sensitive, had a greater positive predictive value and a lower false-positive rate than did the Pap test.
The cobas viral test also involves obtaining cells from the uterine cervix, but instead of microscopic evaluation, the cells DNA is extracted and tested to see if it contains DNA from the HPV virus particularly the strains most likely to cause cancer. If the DNA tests are positive, then the woman also has a colposcopy a test that involves examining the cervix with magnification to determine whether cancerous changes are present.
Thus, a positive cobas test would lead to similar testing as a positive Pap test, but the cobas test could be positive for HPV before any changes would be picked up by a Pap test. A woman in this situation could then be earmarked for more frequent follow-up exams.
The FDA does not have to follow the advice of its advisory panels, but it usually does so. We may soon expect to see the venerable Pap test fall into disuse.
ACHS s Dr. Josh Bloom, a long-time participant in antiviral research noted, Assays that can quantify the presence and amount of a specific virus are often becoming the primary test for an infection. This is a very good development, since much lower amounts of virus can be detected, and the increase or decrease in viral load can be accurately determined. This has huge implications for infections like HIV and hepatitis C. The assays are so sensitive that if viral DNA/RNA cannot be detected it is almost like the virus is no longer present.
