Do mammograms do more harm than good?

For sure, mammograms contribute to the income of radiologists and other professionals who provide medical services to screen for breast cancer as well as the medical device manufacturers.  And, the U.S. Preventive Services Task Force recommends a mammogram every other year for women between 50 and 74, suggesting that for this age group mammograms do more good than harm. But, the Task Force once again does not recommend mammograms for women under 50, concluding that, for younger women, mammograms do more harm than good.

Since the U.S. Preventive Services Task Force last looked at the value of mammograms for women in 2009, according to Shannon Brownlee and Lisa Simpson, “the number of studies of mammography has grown, and if anything, the evidence is even stronger: we are consistently over-diagnosing and over-treating breast cancer — and younger women are paying the highest price.”  There’s a better than even chance that women under 50 who get mammograms for ten years will receive a false positive and need further unnecessary testing, increasing psychological stress and costs for them.

There’s also mounting evidence that between one in three and one in five breast cancers that mammograms detect do not need to be treated or could be treated later in women’s lives.  For now though, doctors cannot know the difference between those cancers that need treatment and those that do not.

The Cochrane Collaboration reviewed seven trials involving 600,000 women between the ages of 39 and 74, half of whom were randomly chosen for screening before a lump could be felt. They reported that the studies with the most reliable data showed that mammography screening did not reduce a woman’s chance of dying of breast cancer.

At the end of the day, women should consult with their doctors about whether they need screening mammograms more frequently than the U.S. Preventive Services Task Force recommends.  They should understand the benefits and harms.  The Cochrane Collaboration has a good information sheet capturing the scientific evidence.

The evidence on mammograms provides powerful reasons to heed the advice of the U.S. Preventive Services Task Force. Today, we collectively spend an estimated $4 billion a year on false positive mammograms and breast cancer overdiagnoses. Without compelling evidence of lives saved and little risk, it’s hard to see the benefits of more mammograms as worth their psychological and financial costs.