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 in February.
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 for Women 40 to 49Leon Gordis, MD, Chairman, Johns Hopkins University |
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 treatment.
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.
