More Evidence of Over-Reliance on Mammography

Another study examining the benefits and risks of routine mammograms has confirmed earlier concerns that, in many cases the tests at best complicate the assessment of breast health and at worst pose significant harm for people whose results show the presence of a small mass.

Writing in the New England Journal of Medicine, the researchers conclude that, “Despite substantial increases in the number of cases of early-stage breast cancer detected, screening mammography has only marginally reduced the rate at which women present with advanced cancer. Although it is not certain which women have been affected, the imbalance suggests that there is substantial overdiagnosis, accounting for nearly a third of all newly diagnosed breast cancers, and that screening is having, at best, only a small effect on the rate of death from breast cancer.”

Although many members of the medical community-radiologists and the American Cancer Society-continue to support regular mammograms for all women 40 and older, it seems that, absent a higher risk for the disease, most women needn’t have the regular screenings. And those who do might benefit more from “watchful waiting” than aggressive treatment for small tumors.

Women at higher risk are those with a family history of breast cancer, those who have genetic mutations known as BRCA1/BRCA2 and those with dense breasts. “Watchful waiting” is monitoring something identified on a screening test that may or may not become dangerous.

Readers of this blog are familiar with the to-and-fro surrounding the wisdom of people at low risk of having both mammograms and prostate tests. The new study says that approximately one-third of the tumors found in routine mammograms probably won’t develop into cancer.

The researchers say that the tests are overused and that improving survival rates from breast cancer are mostly the result of better treatment, not of discovering small tumors earlier through imaging.

The researchers “estimated that breast cancer was overdiagnosed (i.e., tumors were detected on screening that would never have led to clinical symptoms) in 1.3 million U.S. women in the past 30 years. We estimated that in 2008, breast cancer was overdiagnosed in more than 70,000 women; this accounted for 31% of all breast cancers diagnosed.”

As explained on NPR, this means that although mammography is good at catching early tumors, it isn’t catching many advanced breast cancers. Some early tumors never progress to malignancy; they resolve on their own.

So the harm of “overdiagnosis”-treating something that doesn’t need to be treated-is not just the fear that a positive test indicates a probability for cancer, but the risk of false positives that lead to additional tests with their own risks, such as radiation exposure and infection from biopsies. Not to mention the additional cost.

The new study looked at 30 years of breast cancer data.

One breast imaging specialist interviewed by NPR said, “What my friends … want to know is, ‘Should I have a screening mammogram?’ And … this kind of study sometimes raises more questions than it answers.”

A breast surgeon who acknowledges that women might be hopelessly, frustratingly confused about regular screening says it depends on the individual’s medical profile. Women at lower risk might forgo frequent screening, and everyone-women and their doctors-should accept that not all diagnosed breast cancers should be treated to the max.

She used the example of ductal carcinoma in situ (DCIS), when the abnormal cells haven’t spread beyond the milk ducts. It’s often treated with surgery, hormones and radiation, when the patient might do just as well with watchful waiting.

The best way to disperse the fog surrounding the question of whether or not to have regular mammograms is knowledge and communication: Know your family’s medical history, know your own anatomy, know all the risks and rewards of screening and have frank discussions with your doctor. If he or she is unwilling to engage, it’s time to see someone else.