Millions of women undergo regular mammograms because they have been repeatedly told that early cancer detection means a much better outcome. The implied promise: “if you get your annual mammogram we can catch cancer at its earliest stage and reduce your likelihood of dying from breast cancer.”
A new study in the New England Journal of Medicine, however, concludes that this promise has been unfulfilled. In a nutshell the article suggests that catching cancer early has not had a dramatic impact on the development of late-stage cancer or substantially improved long-term outcomes. According to the research, as many as 70,000 women in the U.S. each year (one in three) end up being treated for cancer that would not develop into something dangerous or deadly.
Not surprisingly, this heretical report has stirred up a hornet’s nest of controversy with radiologists and oncologists as well as with women who believe that getting a mammogram is the single most important thing they can do to protect their long-term health.
Everyone assumes that cancer must always be treated. Physicians have known for a long time, though, that a significant number of abnormal (yes, even cancerous) growths will disappear on their own or never become life threatening. This is not a message that has been communicated effectively to the public. Because it runs counter to what people have been told for decades, it drives them crazy. Further complicating the issue, doctors are not good at determining which cancers are “benign” and which are destined to kill. For the most part, however, they have kept this a secret. As a result, they treat just about everyone who shows up with a diagnosis of cancer and most patients are grateful, despite the toll such therapy takes.
The researchers tracked data for more than three decades, ever since widespread screening mammography was introduced in the U.S. in the 1970s. Not surprisingly, the number of early-stage breast cancer cases increased dramatically as a result of mammography. They went from 112 cases per 100,000 women per year to more than double that or 234 cases per 100,000 women. That means that as a result of screening mammography there were 122 more cases of early breast cancer identified for every 100,000 women thanks to mammography.
In theory, this ability to detect cancer at its earliest stages should have led to a dramatic drop in late-stage, serious cancers, and it should have saved a lot of lives. Ideally, one might have expected half as many life-threatening cancers. In fact, the absolute decrease was only 8%. The number of late-stage cancers decreased from 102 cases per 100,000 women to 94 cases per 100,000 women. In other words, only 8 women out of the 122 who were diagnosed early were likely to develop what the researchers called “advanced disease.”
Of course if you were among the 8, you might count yourself lucky. But what about the other 114 women who probably would not have gone on to develop life-threatening breast cancer? The authors of the article suggest that many, if not most, of these women were overdiagnosed. One of the authors, Gilbert Welch, MD, MPH, wrote in the New York Times that more than a million women were told that they had early stage cancer. They were probably not told it wouldn’t have threatened their lives. Almost assuredly most were treated anyway, either with surgery, radiation or chemotherapy or some combination of the three. Dr. Welch maintains that this treatment was for a cancer “that was never going to make them sick.” The treatment is not benign, however. All three therapies–surgery, chemo, radiation–carry their own risks. Both chemo and radiation may increase the risk for other cancers later in life.
When a doctor tells a woman that she has breast cancer, the world starts spinning. In that instant everything changes. Because cancer is such a scary diagnosis, the idea of watching, waiting and doing nothing is virtually impossible for most people. Most women are grateful if the doctor says the cancer has been “caught” early and that treatment will produce a long-lasting remission, if not a cure. The notion that early detection does not actually reduce the number of women who develop life-threatening breast cancer is hard to comprehend.
The most recent research in the New England Journal of Medicine is not the only study to suggest that screening mammography may promise more than it can deliver. Dr. Welch notes in the New York Times that European studies have concluded, “mammography has either a limited impact on breast cancer mortality (reducing it by less than 10 percent) or none at all.”
It is almost impossible for doctors or patients to conceive of overdiagnosis of breast cancer or unnecessary treatment. The bottom line, according to Dr. Welch, is that his medical colleagues need to be more honest. As he points out in the Times, “The truth is, a few breast cancers are destined to kill no matter what we do…While no one can dismiss the possibility that screening may help a tiny number of women, there’s no doubt that it leads many, many more to be treated for breast cancer unnecessarily.”
Just as with prostate cancer, researchers need to learn how to distinguish between the cancers that are “inconsequential” and those that will become aggressive and kill us. Women who are at high risk for life-threatening cancer because of genetics or personal history may indeed benefit from screening mammography, just as men who are at high risk for dangerous prostate cancer may benefit from a PSA test. For many others, though, the idea that they could actually live a normal life with untreated cancer comes as a total shock.
To learn more about this heretical notion, you may wish to listen to a free one-hour interview we conducted with Otis Brawley, MD, chief medical and scientific officer of the American Cancer Society. You cannot find a more established and respected cancer doctor than Dr. Brawley. You will be amazed at what you hear when it comes to the screening and diagnosis of cancer. Please keep an open mind and heart when you listen to this extraordinarily honest interview with one of the country’s leading physicians.
For a more in-depth discussion of mammograms you may wish to read our section on breast cancer and conversation with breast cancer expert Dr. Susan Love in our book, Top Screwups Doctors Make and How to Avoid Them.
We would love to get your comments on this article and Dr. Brawley’s interview below.