For two decades now the medical mainstream has been telling women that mammograms can save their lives. I’m sure that when they started, they believed it was true. But mounting research is revealing the new truth: if anything, mammograms may actually do more harm than good.
Mainstream practices “selective hearing” on the mammogram issue
Last year, an analysis of all available mammography research by two scientists at the Nordic Cochrane Center in Copenhagen, Denmark concluded, “screening for breast cancer with mammography is unjustified.” The Cochrane Center is well known and respected in the medical research community for its rigorous systematic review methods. In this thorough review of seven of the largest mammography studies from around the world, the Cochrane scientists found that “there is no reliable evidence that screening decreases breast cancer mortality.” The study was met with solid resistance and sharp criticism. The medical community effectively covered its ears as if to say, “I’m not listening!” After all, think about how many women they’ve sent to have this test. They needed to believe they had been doing the right thing.
Now, those same authors are back with another study. In response to the heckling they endured last year, they re-examined their data and subjected it to even more rigorous analysis. This time the results are even harder to ignore.
As the authors stated in a research letter in the British medical journal The Lancet, the second analysis just “confirmed and strengthened” their previous findings. They still found no benefit from mammograms. In fact, they found that they may actually be harmful, as women who were screened with mammograms were much more likely to undergo a mastectomy, lumpectomy, or radiation treatment. And according to their evidence, these invasive procedures did little to save women’s lives – and may actually put them in harm’s way.
Mortality rates show no overall decline with screening
How can this be? For two decades now they’ve been telling us that regular mammograms allow women to catch cancer early, while it’s still easily treated. Women over 40 are told to get a mammogram every year – and millions of women have been dutifully following that advice.
The authors say the recommendations are based on flawed studies and flawed logic. Previously published studies showing a benefit from mammography were poorly designed and incorrectly interpreted. Many showed a reduction in deaths from breast cancer, while failing to show a reduction in deaths overall – a discrepancy that didn’t make a lot of sense. When the authors dug further, they found the studies often misclassified the cause of death with a bias in favor of mammograms. When studies used overall mortality as the main outcome measure, they failed to find any benefit from screening.
They also question the assumption that mammograms catch tumors during a small and critical window of treatment opportunity. The entire screening theory is based on the supposition that if you detect cancers while they are still too small to be felt, they can be cured. But in reality, the authors say there is little evidence to support that.
They point to two studies that support their position. The first, conducted in Malmo, Sweden, compared the experience of 21,088 women who had mammograms to 21,095 women who did not. After nearly nine years, 63 women in the mammogram group and 66 women in the control group had died of breast cancer. The second study, performed in Canada, tracked 44,925 women who had mammograms and 44,910 controls. Among this group, 120 of the screened women died of breast cancer, while 111 women in the control group died of the disease.
Screening increases surgeries by 30 percent
Proponents of early screening have also claimed that it can reduce the need for surgery, as smaller tumors found earlier could be treated in other ways. But this claim didn’t bear out in reality. The researchers found that women who underwent regular screening had about 30 percent more mastectomies and lumpectomies than women who weren’t screened. They also found that tumors detected by mammograms are likely to be treated with radiation, which carries a real risk of cardiovascular damage. As the authors wrote, “as screening primarily seems to identify slow-growing tumors, the adverse effects of treatment could potentially reduce or even neutralize any possible benefits.”
According to the New York Times, this study has lead Swiss officials to abandon plans to offer a national mammography screening program. But so far, the rest of the world is still covering its ears. Officials at the American Cancer Society dubbed the study “unconvincing.” They plan to continue to tell women to get regular mammograms each year, and to spout their mantra that mammograms save lives.
None of us should assume that a yearly mammogram will save us from breast cancer – or that surgery and radiation are the only acceptable responses to a positive reading. As this study shows, there are many more variables to consider and many more assumptions to challenge before jumping on the mainstream bandwagon. If nothing else, you should insist that your doctor consider this analysis before ordering annual mammograms.
Sources:
Lancet 2001; 358: 1340-1342
Lancet 2001; 358: 1284-1285
Lancet 2000; 355: 129-134
Copyright 1997-2002 by Institute of Health Sciences, L.L.C.
