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An independent panel of experts
said January 24 that there was insufficient evidence to show that mammograms
prevented breast cancer deaths.
The group, which meets regularly
to assess evidence on cancer and provide that information to doctors and
to the public, said that while it was possible that mammograms were beneficial,
it was also possible that they were not.
The group, called the P.D.Q.
screening and prevention editorial board, agreed here today that seven
large studies of mammography had serious flaws, weakening or
casting doubt on the studies' validity.
The group, which writes information
for the National Cancer Institute's online database, said that it would
rewrite previous statements to reflect its new view.
Previously, the group, which
does not make specific recommendations for medical practices, had said
that the evidence showed that mammograms prevented breast cancer deaths
starting at age 40.
The decision by this group
clouds a continuing debate over whether women should have regular mammograms.
Since 1997, the National Cancer Institute has also recommended that women
have regular mammograms, starting in their 40's.
For now, the cancer institute,
whose new director, Dr. Andrew C. von Eschenbach, was sworn in on January
22, has not announced any plans to revisit the issue, raising the question
of whether the Institute will end up with conflicting information on its
Web site, with one statement saying that the screening is beneficial and
another saying that those benefits have not been proved.
The institute's Web site, www.cancer.gov,
says that women in their 40's and older should have the test and that
it reduces the breast cancer death rate by as much as 30 percent.
Members of the P.D.Q. board
said they knew that it was not going to be easy for women and doctors
to decide what to do. At the meeting, the members wrestled with the question
of how much benefit, if any, mammograms confer. Some, like the board chairman,
Donald A. Berry, chairman of the department of biostatistics at M. D.
Anderson Cancer Center in Houston, said they
thought it was unlikely that there were benefits that could make the test
worthwhile.
But others said that they were
uncertain and that they were having a hard time coming to terms with the
profound flaws they now saw in studies they had thought put mammograms
on solid ground.
"What this new material
has contributed is a softening, at least in my mind, of what I thought
was true," said Dr. Isra Levy of the Canadian Medical Association.
"I still think that for women aged 50 to 69 there might be something
there. But we've had our confidence shaken."
In the end, the group decided
not to deal with age, saying doubts persisted for women of all ages.
The group focused on flaws
in the studies that were recently uncovered by two scientists in Denmark.
The report, published in October by Dr. Peter C. Gotzsche and Ole Olsen
of the Nordic Cochrane Center in Copenhagen, concluded that the case for
the screening was unproven.
The studies were so poorly
designed and carried out that they might have found benefits when there
were none or exaggerated what benefits there were, the researchers said.
None of the studies found that
mammography prolonged life, and even when the studies were analyzed as
a group, women who had the test lived no longer, dying of diseases other
than breast cancer.
Some experts have taken issue
with Dr. Gotzsche and Mr. Olsen's analysis. But today, the P.D.Q. Board
said it believed that the scientists had found serious problems.
The board's assessment of mammography
is expected to be posted on the cancer institute's Web site in April.
The P.D.Q. Board said it would
like to see others take on a detailed and independent analysis of the
mammography studies and that some of the data that might settle questions
about the quality of the studies could be obtained with difficulty.
The issue of whether women
should have mammograms has been controversial for some time. In January
1997, when an independent panel convened by the National Institutes of
Health took on the question of mammograms for women in their 40's, Congress
got involved.
That panel said then that there
was no evidence that the test prevented breast cancer deaths in women
under 50 and suggested that those women discuss mammograms with their
doctors before deciding to have one.
Before the week was over, the
panel's chairman, Dr. Leon Gordis of the Johns Hopkins University, had
been summoned by Senator Arlen Specter to testify before Congress. Later,
going against the conclusions of the panel convened at its behest, the
cancer institute said women in their 40's should have mammograms.
The P.D.Q. Board, which issues
its statements independently, has also said over the last several years
that mammograms prevent breast cancer deaths for women in their 40's.
Today, the P.D.Q. Board emphasized
that mammograms have drawbacks, leading at times to excessive treatments
for tumors that would not have threatened a woman's life.
The group agreed that
doctors should respect a woman's decision, adding that it was
rational to decide to have mammograms and that it was rational to decide
not to.
Whatever they decided, Dr.
Berry said in a telephone interview on Tuesday that he was acutely aware
of the difficulty in questioning an enormous mammography business.
"Screening programs bring
in patients," Dr. Berry said. "It isn't just the mammography,
but it's the biopsies, the surgeries and the like. We know that screening
is exquisitely fine at finding cancers. Therefore it brings in patients
and they demand treatment."
The problem, he said, is if
the women who have mammograms fare no better, or do even worse because
of excessive treatment, than women who are not screened.
New York Times January
24, 2002
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