Scientists have known for some time that virtually all cases of cervical cancer
are triggered by a family of viruses called human papillomavirus, or HPV. Most
women who become ineffected with HPV are able to shake off the virus and suffer
no apparent long-term consequences to their health. But a few women develop a
persistent infection that can, for reasons that are not entirely clear,
eventually lead to cancerous changes in the cervix. Now
researchers at the Digene Corp of Beltsville, Maryland, have developed a test
that detects an active HPV infection by looking for its genetic byproducts in
the vagina. The HPV test was better than the standard Pap test at finding
cervical cancer at any stage, according to two studies published this month in
the Journal of the American Medical Association. So far, so good. Unfortunately,
the test's false-positive rate-how often it indicated that there was a problem
when none existed was almost twice as high as that for the Pap smear. In these
cases, a biopsy of the woman's cervix showed no sign of disease.
And that's the crux of the problem. How many women should undergo what
is, when it comes right down to it, unnecessary treatment to find a few more
cases of cervical cancer? Shouldn't health officials focus instead on making
sure that more women undergo regular Pap-smear examinations? After all, Pap
smears, though far from perfect, have helped dramatically lower the death toll
from cervical cancer taking it from the No. 1 cause of death due to cancer in
American women to the 10th. Complicating matters is the fact
that HPV is a very common infection. In some parts of the U.S. as many as half
of all women under age 35 have an active case. Yet 99 out of 100 women who are
HPV-positive will never get cervical cancer, estimates Dr. Joanna Cain, vice
president of the American College of Obstetricians and Gynecologists. "If those
99 women live their lives as if they're going to develop cancer", she says,
"we're not necessarily doing them any good." At present, the
HPV test is approved in the U. S. only to help resolve ambiguous results from a
Pap-Smear test. Many gynecologists believe that HPV will eventually replace the
pap. But they're not willing to abandon it without a lot more detailed
information and neither should you.
单选题
The cause of cervical cancer was discovered by American scientists some
time ago.