Don't women have enough to worry about? Breast cancer is scary enough without all the recent confusion about mammography. That's the sad but true state of the science today, and science simply refuses to be rushed, hyped, or intimidated by doctors, pressure groups, or even the government.
All these years at least since the '80s docs have been telling women between ages 40 and 65 or so to get annual mammograms to catch breast cancer early and thus have a better chance of curing a smaller lesion. (Some clinicians have actually been following guidelines which call for mammography only every two years for younger women, but many have not). Now comes a report from Danish researchers supporting their prior analysis published in 2000 who assert that there is no valid evidence to support mammography's usefulness in reducing the risk of death from breast cancer. These studies were published in the internationally-respected medical journal, The Lancet, and their conclusions were adopted (at least for women aged 40-49) by a National Cancer Institute advisory panel, the PDQ. It should be noted that these reports unveiled no new data; they merely re-analyzed information gleaned from seven older studies. The Danes basically threw out five of these studies as being substandard, in light of today's research parameters. Evidence from the two that were left did not suggest to the researchers that mammograms meet their standards of medical efficacy.
Rushing to the defense of mammography as a life-saving screening tool the accepted factor was a 30% reduction in mortality among those women screened were a spectrum of medical organizations, breast cancer advocacy groups, and the NCI itself. Articles and letters appeared, both in the lay and academic press, supporting the current recommendations for screening. Since breast cancer will be diagnosed in approximately 200,000 American women this year and is predicted to kill over 40,000 (making it the second leading cancer killer in women after lung cancer), there is much to be gained, or lost, in this debate.
Supporters of continued widespread use of mammography screening note that, while the incidence of newly-diagnosed breast cancer has gone up slightly in recent years, the death rate has declined significantly. They conclude that mammograms have caught more growths at curable stages, while opponents note that better treatments, including chemotherapy and so-called "selective estrogen modulators" such as tamoxifen, have been responsible for lower death rates, and not the breast x-rays. Supporters point out that in recent years average tumor size is smaller than twenty years ago, thanks to mammograms, and if nothing else this has allowed less-invasive operations for their removal. Opponents say that too many women get costly, dangerous, and scary surgical interventions for non-malignant "lesions" seen on mammograms called false-positives by the profession. A recent study showed that over a ten-year period, for women who had regular mammograms, the chance of a false-positive result was almost 50%; the chance of an unnecessary biopsy was almost one in five over that same period.
No one is saying that mammograms are a perfect, or even an excellent screening tool. Besides the aforementioned false-positives, there are significant numbers of missed lesions called false-negatives. These devastating misses occur more commonly in younger women more than 20% of the time, in fact whose denser breasts lead to confusion between normal and cancerous tissue on mammograms. Some women are destined to experience spread of their cancer, even if a growth is detected when small and apparently curable; their cancers are highly malignant, and have already spread when discovered. And some less-malignant growths will never spread, even if untreated, but it's not possible to distinguish growths with lethal potential from more benign ones on mammograms.
Even the critics agree: no one is saying that mammograms _don't_ save lives, merely that we are now less certain that this is so than we were before. If mammograms do save lives, at what cost? I don't mean financial, although the expense is a worthy subject for discussion (we should keep those costs in mind when 30 million such tests are done in one year in this country alone). I refer mainly to the cost in terms of lives saved versus distraction from other, perhaps more effective and precise techniques to diagnose early breast cancers. Have we been lulled into a false sense of security by our slavish devotion to the mammogram mantra? Maybe we would have developed better ways to find curable breast tumors by now if we hadn't succumbed to the clinical inertia of always doing what we did before, thinking the studies had been done and the answer was in, end of story.
What do we do now, as I asked at the outset? There is no obvious answer, but until more reliable information is obtained, it is almost certain that women and their doctors will be unwilling to stray from what has been recommended over the past twenty years or so. Well, why not, you might ask? What's the harm? Mammograms don't hurt anyone, do they? But if mammograms don't effectively save lives, they do indeed have the potential of doing great harm, both passively (giving a false sense of security) and actively (leading to unnecessary procedures). We cannot unthinkingly continue our previous practice; neither should we (perhaps prematurely) discard a method we have grown comfortable with. More valid data must be obtained to justify our endorsement of prior recommendations, either by thorough audit/review of previous studies, or (preferably) by doing new, controlled trials of randomly selected populations getting screened as compared to those not getting screened. While the latter is bound to be a tremendous undertaking, it must be done too much is at stake to avoid it any longer. America's women, and those who love them, must benefit from the best possible data.