NEW YORK, Jun 23 (Reuters Health) - The sexually transmitted human
papillomavirus (HPV) can increase a woman's risk of cervical cancer. Now, two
studies suggest that consistently high levels of the virus--in addition to the
type of virus--can help predict if a woman is likely to get cancer years in the
future.
There are about 100 different types of HPV, some that cause genital warts
and some that are completely symptomless, but only a handful of them increase
the risk of cervical cancer. In many cases, the body can successfully combat the
virus, which eventually disappears from the cervix.
About 40% of women have symptom-free HPV infections and 5-10% will have an
abnormal Pap smear due to the virus. Less than 1% will develop cervical cancer.
In the two studies reported in the June 24th issue of The Lancet,
researchers looked at levels of a particular high-risk virus, HPV 16, in women
over time. They analyzed how the virus affected their Pap smears--the
traditional test in which doctors collect cells from the cervix and analyze them
for signs of cancer.
In the first study, Dr. Agnetha Josefsson with the University of Uppsala in
Sweden and colleagues found that women with the 20% highest amount of HPV 16 had
60 times the risk of being diagnosed with cervical cancer an average of 8 years
later compared with HPV-free women.
They conclude that testing for HPV levels during routine gynecological exams
"might strikingly improve our ability to distinguish between infections that
have a high or low risk of progressing into cervical cancer."
In the second study, Dr. Nathalie Ylitalo from the Karolinska Institute in
Stockholm, Sweden, along with Josefsson's team of researchers, reviewed nearly
4,000 Pap smears from about 1,000 women taken over 26 years. The researchers
found that those women who developed cancer had consistently high levels of the
virus 13 or more years before being diagnosed--often at a point when their Pap
smears were completely normal.
Women with consistently high levels of HPV 16 were at least 30 times more
likely to develop cervical cancer than women who did not test positive for HPV
16. They also found that 25% of women with high levels of the virus before age
25 developed cervical cancer within 15 years.
The authors suggest that a test to measure levels of HPV 16 may help to
identify which women with normal or slightly abnormal Pap smears are at risk for
future cervical cancer.
However, Dr. Carolyn Johnston of the University of Michigan Hospital in Ann
Arbor, Michigan, questions whether such tests will be any better than the
traditional Pap smear. There is no vaccine or treatment for symptom-free HPV
infections, she notes in an accompanying editorial.
"If these suggestions are carried out, several questions arise," she writes.
"What should be done for these ostensibly high-risk women, once they are
identified?" It's not clear that "any of these new tests will be a substantial
improvement to the accessibility, cost, and positive-predictive value of the Pap
smear," she concludes.
