In a major reversal, the National Cancer Institute is announcing plans to change its own guidelines on recommending mammograms for premenopausal women.
Instead of urging that all women aged 40 to 49 be screened every year or two with mammograms, a position the institute has held since 1987, the NCI, citing inconclusive evidence from eight randomized trials and controversy among specialists, is now proposing that women under 50 get the X-rays only when advised to do so by their doctors.
The institute is not saying that younger women should not have regular mammograms, nor is it suggesting that mammograms are dangerous. The NCI's proposed rules merely say that regular mammograms are not automatically recommended for younger women.
In proposing the changes -- which will be discussed tomorrow at the National Institutes of Health, NCI's parent agency, and which could become final in December -- the NCI cited a lack of proof that screening mammograms save lives for younger women.
The proposed changes, detailed in today's issue of the Journal of the National Cancer Institute, stem from a workshop the NCI convened in February at which experts evaluated the results from eight studies of nearly 500,000 women aged 40 to 74 in the United States, Sweden, Great Britain and Canada over the last 30 years.
Taken all together, that evidence showed clearly that for women aged 50 to 69, screening mammography reduced breast cancer risk by 30 percent in the five to seven years after entry into the study. Too few women over 70 were included in the trials to assess mammography's effectiveness for them, although there is a high risk of cancer in this group. (Screening mammography refers to using X-rays in a whole population, including women with no symptoms of breast cancer.)
But for women aged 40 to 49, the trials showed "no screening benefit five to seven years after study entry, with only marginal and uncertain mortality reductions apparent after 10 to 12 years of follow-up," the NCI said.
Even the head of NCI, Dr. Samuel Broder, expressed ambivalence yesterday. In a telephone interview, Dr. Broder said that as an individual doctor, he would still recommend mammograms for women aged 40 to 49. Yet as head of an agency that must try to come to terms with a mass of confusing studies, he said, the NCI "simply cannot dictate to people and say, 'This is the right way' or 'This is the wrong way.' We have to say, basically, that the experts do not agree. We can't simplify that artificially."