Breast Cancer: To Screen or Not to Screen

Join us online today at 11 a.m., as Boston Medical Center radiologist Dianne Georgian-Smith answers questions about the new breast cancer screening guidelines in a live 45-minute BU Today Web chat. Below, Phyllis Kornguth, a School of Medicine professor of radiology and BMC section head of breast imaging, talks about the issue with BU Today.

Women over the age of 40 were thrown into a health-care quagmire last week when a report from the U.S. Preventive Services Task Force, an influential federal advisory board, recommended that unless they are at high genetic risk, they should not begin routine mammograms until age 50, contradicting well-established advice that those 40 and older should be screened. The group also recommended that women between the ages 50 and 74 be screened every two years, not every year.

The change of medical mind was based on several studies showing a very small statistical gain from great numbers of tests that often led to unnecessary and harmful treatments. Donald A. Berry, a statistician at the University of Texas M. D. Anderson Cancer Center and head of one of the research groups behind the decision, says in the New York Times that the benefits of screening every year instead of every two years are “so little as to make the harms of additional screening come screaming to the top.” The task force concluded that when women have mammograms every other year instead of every year, those harms are cut in half, but the benefits are almost unchanged.

In a torrent of media coverage, the American Cancer Society, the Susan G. Komen Breast Cancer Foundation, and high-profile oncologists and radiologists across the nation are urging women between 40 and 50 to ignore the report and continue both routine mammography and breast self-examination. BU Today spoke about the dilemma with Phyllis Kornguth, a School of Medicine professor of radiology and section head of breast imaging at Boston Medical Center.

BU Today: Are these task force recommendations likely to change anything?
Kornguth: They might. This is an independent but influential group that speaks to primary care providers. They go through the medical literature and guide physicians, advising them what screening tests are meritorious. I would say that if primary care doctors follow these recommendations, then yes, things will change. And I think the change would be disastrous.

According to the American Cancer Society’s chief medical officer, the task force is saying that “mammography at age 40 to 49 saves lives, just not enough of them.” Is this what its review of breast screening studies concluded?
Since 1997, the task force has looked at eight randomized trials of women of all ages in the United States and other countries. The first study concluded screening of women under 50 was beneficial, and in a 2002 review the task force came to the same conclusion. These new recommendations are based on the same studies, with one dropped and a new one added. They’ve reinterpreted the same numbers using computer models. It’s just mind-boggling. But the numbers don’t matter. What the task force is saying is that rather than saving lives, these younger women shouldn’t be made anxious from false positives. That’s wrong. The mood in the profession is one of total disbelief.

What would you say to women who are confused and concerned about this reversal of the prevailing wisdom?
Right now women should stay with the guidelines. All of the information isn’t in. But the scientific evidence so far shows that screening works. It finds breast cancer early and in cases where it can be cured.

But isn’t there a significant downside to mammography? Aside from radiation exposure, aren’t there many false positives and the possibility of overdiagnosis?
I’ve been a mammographer for ages. The vast majority of callbacks do turn out to be nothing. You can’t be in this business and not realize the negative aspects of mammography. Is it a perfect test? Oh my God, no. Even under the current guidelines, we miss 10 to 15 percent of cancers. That’s a downside. The radiation dose has been lowered to a ten-thousandth of what it was back in the 60s. Of course the dangers of radiation are cumulative, even after five years, not two. Yes, there are lots of downsides, including true anxiety, and maybe overtreatment. But I find these task force recommendations disturbing.

What about task force members’ saying that routine mammography for women under 50 sometimes leads to treatment that’s not just unnecessary, but painful and life-altering?
How do I answer the question that women are suffering unnecessary anxiety or unnecessary painful treatment? It’s part and parcel of an imperfect test. On the other hand, they’re equating those evils with breast cancer. C’mon, let’s get real. If you’ve got a population of people that harbor breast cancer, and you’re telling me they may suffer from extra treatment, you can’t equate that with missing cancer. We’re talking about two different things.

Is it a matter of mammography, imperfect as it is, being the only effective screening method for the small number of breast cancer cases in women under 50?
Yes, it’s inexpensive enough; it’s available enough. The two crucial tests are physical examination and mammography. MRI is much more sensitive, but much more difficult to do and has a much higher rate of false positives. Some people say we’re overtreating breast cancer. It’s true that a very small percentage of screenings go to biopsy and a very small percentage of those cases go to cancer. There’s a form of breast cancer called DCIS (ductal carcinoma in situ) that some say we shouldn’t treat so early. But the answer for that is not yet in. In breast cancer, we don’t know for sure if these progress if they’re left alone. In a few studies, there have been women who have refused treatment for DCIS, but some of these cancers go on to be invasive. The problem with screening and diagnosis is, say I go in for biopsy and it comes out DCIS. Nobody can say it won’t lead to cancer. Am I not going to get treated? We’re between a rock and a hard place. We don’t have the answers yet. But to tell people not to get mammograms is just mind-boggling.

The risk of breast cancer in women under 50 remains low, doesn’t it?
If you take a thousand women and screen them for the first time, you’ll find six or seven cancers. If you take women who have been screened before, you’ll find around three cancers. Not a huge epidemic, is it? Do I like exposing 997 women to X-rays to find those three cancers? No. But I’ve got to advise you that screening translates into decreased mortality. I would rather there be a definitive blood or urine test and refer women to mammography only to find cancers we know are there. It would make my life so much easier. It’s not a perfect world yet. But this recommendation isn’t helping.

Susan Seligson can be reached at sueselig@bu.edu.