Washington. -- As the premier government agency for dealing with the most feared disease, the National Cancer Institute should realize that the average citizen is not certified in oncology or statistics.
Clarity and explanatory skill are required when professionals address lay people about cancer. But these qualities have been scarce in the institute's declarations concerning one of the most complex issues in cancer diagnosis, mammography for breast cancer. In this matter, the cancer institute has made the worst of a difficult situation.
The ingredients behind this sad performance are detailed in a new report by the House Committee on Government Operations. The story of the National Cancer Institute and breast-cancer advice was eclipsed by the election campaign, but it should not be lost.
Last December, the institute issued a statement saying that for women ages 50 and over, mammography and clinical breast cancer examination every year or two "can reduce breast-cancer mortality by about one-third." Nothing new or ambiguous in that.
But then the statement proceeded: "Experts do not agree on the role of routine screening mammography for women ages 40 to 49. To date, randomized clinical trials have not shown a statistically significant reduction in mortality for women under the age of 50."
Carefully drafted, the statement didn't come out for or against mammography for women 40 to 49. Rather, it said we've found no evidence that it will prolong life for this age group, in which almost as much breast cancer occurs as in women over 50. The major difference in diagnoses arises from denser tissue in the younger women, which reduces the efficacy of mammography.
Strangely omitted from the medical communique was a jarring fact: In 1987, the cancer institute formulated a guideline endorsing mammography for women ages 40-49. A dozen other health organizations, including the American Cancer Society, took that position and stuck with it, despite the National Cancer Institute's sudden turnabout in 1993. Even its top advisory group, the National Cancer Advisory Board, opposed the change.
Without acknowledging that it had changed its position, the institute described its statement as "a successor to a 'working guideline' formulation drafted in 1987."
The statement didn't say so, but mass mammography is expensive, carries a slight risk of radiation damage for some patients, and can produce false alarms. The experts thus felt duty-bound to report their findings, derived from the best-available studies of the life-saving benefits of mammography. Patients as well as doctors were, of course, puzzled and confused by the cold statistical findings, but the facts couldn't be disputed: Studies had failed to detect any life-saving value of mammography for women 40-49.
But how reliable were the studies? The House committee report notes that several of the National Cancer Institute's own senior scientists disputed their quality and advised against changing its position on mammography. One of the scientists, Charles Smart, former branch chief of the Early Detection Unit, complained that the workshop that led to the revised position was "stacked." Another described it as "loaded."
The committee report quoted numerous criticisms of a recent Canadian study that reinforced previous doubts about the value of mammography for women 40-49. The study had been faulted for poor screening of patients, inadequate training and statistical deficiencies. Of the seven other studies examined by the National Cancer Institute, the report continued, none was designed to test screening in the 40-49 age group. The congressional report points out that at a meeting of the International Union Against Breast Cancer in 1993, "NCI joined representatives of the international scientific community in unanimous agreement that these trials had insufficient statistical power."
Obviously startled and concerned by the medical and political reaction to its ham-handed performance, the institute is now considering a conference to re-evaluate the available scientific wisdom on mammography for women ages 40-49.
The first round of experts may indeed have been right about the worthlessness of mammography for this group. But for pure ineptitude in addressing the public on a fearsome subject, the National Cancer Institute's performance would be hard to beat.
Daniel S. Greenberg is a syndicated columnist specializing in the politics of science and health.