We are on a search for truth, but will we ever find it? That summarizes how I feel after reading an article in today's New England Journal of Medicine, which once again raises the question of how much screening mammography contributes to the progress we have made in reducing deaths from breast cancer in the United States, and by inference, in other parts of the world.
The research paper-written by Dr. Gilbert Welch and Dr. Archie Bleyer, two highly regarded researchers-concludes that over the past 30+ years, screening mammography has contributed modestly, at best, in the progress we have made in decreasing death rates from breast cancer. In contrast, based on their analyses, the doctors conclude that much of the gains we have seen are due to better treatment. An additional observation is that 31 percent of the women diagnosed and treated for breast cancer in 2008 - that's more than 70,000 women - were in fact treated unnecessarily, since if left alone or not diagnosed their cancers would never have caused them a problem during their lifetime. In contrast, they say, these women have endured surgery, perhaps radiation and chemotherapy, all of which have serious consequences and in fact did not contribute to their health or their longevity.
This is not the first research that has been done on this very important-and very emotional--topic nor is this the first time that the question of "over diagnosis" and "over treatment" of breast cancer has become part of the national debate over the value of early detection of breast cancer.
As the authors acknowledge, there has been a considerable body of research that has tried to answer the question regarding the value of mammography, and assess the "harms" of screening mammograms (which, for the patient may include repeat examinations such as additional mammograms, ultrasound and MRI, and for some women, breast biopsy in order to determine whether or not a suspicious lesion is in fact cancer). There have also been a number of studies-some of which are included in an online table which accompanies the Welch and Bleyer report-which try to determine how many women were treated for their breast cancer without health benefit.
So let's acknowledge two basic principles:
One: Many experts agree with the principles espoused in this current report. Yes, some women do have to undergo additional studies to determine if something seen on a screening mammogram is in fact a cancer.
Two: many experts acknowledge that we do treat some women who would otherwise have done perfectly well had we not found their breast cancers in the first place. More...