BETHESDA, Md--The NIH Consensus Development Conference was unanimous
in its decision not to recommend routine screening mammography for women
aged 40 to 49, saying that the evidence to date does not show that any
possible benefits outweigh potential risks.
The panel's draft report recommends that women in their 40s evaluate
their own risk factors and decide for themselves in consultation with their
physicians whether to be screened.
The draft report was not without support from members of the audience,
but its framers faced passionate criticism from many cancer specialists.
Debate climaxed with a statement by Richard D. Klausner, MD, director of
the NCI, who disagreed with the committee report. "My own evaluation
is that the data supporting the benefit of initiating screening in the
40s is stronger now than it had been," Dr. Klausner said. "It
does look significant, and women need to know that." He will present
the findings to the president's National Cancer Advisory Board for review
Concerns and criticisms voiced at the meeting centered around two main
issues: Did the panel appropriately assess new evidence provided by the
most recent randomized controlled trials and did it give too much weight
to potential and theoretical harm associated with mam-mography? Another
issue concerned the omission of high-risk groups, especially African-Americans,
from the studies upon which the panel based its decision.
Dr. Laszlo Tabar, director of mam-mography, Falun Central Hospital,
Sweden, said the panel failed to adequately consider the results of four
randomized controlled trials conducted in Malmö, Kopperberg/Östergötland,
Stockholm, and Gothenburg, Sweden. Results of these trials show an overall
reduction in mortality from breast cancer of 23% for women in their 40s
who undergo screening mammography, he said.
"It seems clear," Dr. Tabar argued, "that while the size
and timing of the mortality reduction rate will require further research,
the existence of such a reduction is no longer in question."
R. Edward Hendrick, chief of the Department of Radiology, University
of Colorado Health Sciences Center, charged the panel with ignoring studies
showing benefits and ignoring "the meta-analyses of those data, which
show that there is a statistically significant benefit."
Ingvar Andersson, of the University Hospital, Malmö, said that
he was skeptical about the appropriateness of screening for younger women.
His own study showed that annual screening of 10,000 women aged 40 to 49
would save only 15 breast cancer deaths over a 10-year period, at the cost
of 1,250 false-positive results requiring further testing. Nevertheless,
he agreed with Dr. Tabar that the draft statement does not properly reflect
the state of knowledge today.
The panel was appointed by the NIH's Office of Medical Applications
of Research. To ensure impartiality, members could not have written on
the subject or have a financial stake in the recommendations. Members read
more than 100 papers and heard from 35 experts at the two-day meeting.
Committee Members: NIH Consensus Development For Breast Cancer Screening
Conference chair Leon Gordis, of Johns Hopkins, insisted that data from
all recent studies were considered and that the evidence presented was
not sufficient to warrant a change in policy.
The draft report was revised, however, to indicate that although randomized
controlled trials show no difference in breast cancer deaths within 7 years
between women assigned to receive or not receive mammography screening,
"summary data from these studies have shown an increasing trend in
favor of mammog-raphy with longer-term follow-up."
The panel maintains that not all women diagnosed with cancer are helped
by early detection. The report pointed out that ductal carcinoma in situ
(DCIS) may not progress to invasive cancer and there is danger of inappropriate
Other risks include the false assurance of false-negative readings,
anxiety caused by false-positive reports, and discomfort during the procedure.
In addition, radiation exposure brings a theoretical risk of one additional
cancer death per 10,000 women tested annually, the report said.
Many radiologists, however, said that the potential risk of radiation
was overstated and that the psychosocial conse-quences of a false-positive
or even a false-negative result were insignificant when compared with the
value of early detection. Critics also pointed out that therapy for DCIS
is changing and overtreat-ment is less of a concern than in the past.
The committee recommended that the costs of mammography for women in
their 40s who choose it should be reimbursed by insurers or covered by
HMOs. In fact, a bill has been introduced into the House by Rep. Jerrold
Nadler (D-NY) that would prohibit insurers from denying coverage for yearly
mammo-grams to women age 40 and above.