SAN FRANCISCOThe Pap smear has long been one of the great
success stories of gynecologic oncology. In the 50 years it has been
used, it has reduced the death rate from cervical cancer by 70%.
Now several new technologies hold promise for catching more cervical
abnormalities than ever before, Patricia Brawley, MD, professor and
chief of the Division of Gynecologic Oncology, Louisiana State
University, told Oncology News International. Dr. Brawley spoke by
phone during her appearance at the 30th Annual Meeting of the Society
of Gynecologic Oncologists (SGO).
Although the traditional Pap smear is now a widely accepted
technology, there is still room for improvement, Dr. Brawley
said. Statistics tell the story: 50% of women with cervical cancer
have had a Pap smear within the last 3 years. Yet studies show that
the sensitivity of the traditional Pap smear is just 51%. The
reason the Pap smear picks up cervical cancer so often is that this
disease is a slow-developing abnormality, Dr. Brawley said.
And in many women, the test is repeated fairly often.
The FDA has approved three new Pap smear technologies. They include
ThinPrep, a test in which cells are collected off the cervix and then
put into a vial of fixative. The other two are computerized screening
tests used with the traditional Pap smear (Papnet and AutoPap).
Computerized screenings enable scientists to catch abnormal cells
that would have been missed by the human eye. ThinPrep has at least
one advantage: It has been shown to decrease the false-negative rate
The good thing about ThinPrep is that it addresses all the
reasons why we have false negatives, Dr. Brawley said.
When we use a slide, sometimes all the abnormal cells dont
get on. With ThinPrep, were increasing the number of cells
that are available for screening because we collect them into a
vial. These cells are more representative, she added.
Cervical cells collected with ThinPrep are also more easily broken
up, she said. It is easier to remove blood and inflammatory cells
from clumps of cervical tissue. And that makes the cervical cells
easier to interpret.
Another problem with the conventional Pap smear is that often the
collected cells are not well preserved. ThinPrep, however, makes it
easier to preserve cervical cells.
Atypical Squamous Cells
The conventional Pap smear does not allow accurate interpretation of
atypical squamous cells. Ten percent of all conventional Pap
smears turn up these cells, Dr. Brawley said. Most
patients within that group have no problem. But in 20% of that group,
well find a preinvasive lesion, she said.
Physicians often struggle over what to do when a Pap smear finds
these atypical squamous cells but cannot reveal if the cells are
preinvasive. Theres a huge number of patients who have
these minimally abnormal cells. And doctors find it hard to decide if
they should do a colposcopy. Its costly and uncomfortable. In
todays legal climate, doctors often have a lot of anxiety about
what to do. Their dilemma is that there is a small number of women
with real abnormalities buried within a large group of these
patients, she said.
The good news, Dr. Brawley said, is that ThinPrep decreases the
number of atypical cells found in smears. Its just a more
accurate test, she said.
Unfortunately, not all obstetrician-gynecologists offer these new
tests. The cost of the new Pap smears are, in fact, a point of
contention. The new Pap smears add $15 to $25 to the cost of the Pap
smear. And many laboratories are already losing money doing the
traditional Pap smear. A Pap smear now costs $10. So using the
new technologies doubles or triples the cost, Dr. Brawley said.
Still many health plans already cover the cost, she added.
Another difficulty with the new technologies is that pathologists and
technicians have to be retrained to use them. The retraining takes
about a week, but not all labs are willing to bear the brunt of the
cost. Many national commercial labs, however, are starting to offer
the new tests.
The real question for many physicians, however, is whether the
survival rate for cervical cancer will increase with use of the new
Pap smears. The American College of Obstetricians and
Gynecologist has, in fact, taken a position that the new Pap smears
shouldnt be accepted as a standard of care until theyre
proven in prospective studies, Dr. Brawley said.
But that kind of study would be almost impossible to conduct, she
added. We would have to follow a huge number of women because
the death rate from cervical cancer is so low. And its not
ethical to do such a study in which you would be denying some women
advanced technologies, Dr. Brawley concluded.