Researchers Caution That Mammograms Sometimes Do More Harm than Good

In a new study, researchers have concluded that mammograms may do more harm than good. Breast cancer screenings can lead to overtreatment since many of the detected tumors are small and harmless. The details are in a paper that was just published in the New England Journal of Medicine.

Mammograms have long been recommended to screen for breast cancer before symptoms begin. The idea is that by detecting tumors early, treatments may be more effective. Medical advancements have improved breast cancer treatments significantly, however, and some doctors are beginning to question the value of these screenings.

Researchers analyzed data from 1975 to 2012. The data came from surveys, databases, and breast cancer registry statistics. They compared death rates before and after mammograms became common as well as the size of detected tumors.

The team found that the increase in the number of tumors found in screenings was due to smaller tumors being detected. Many of these small tumors are harmless but are treated just the same, possibly leading to overtreatment. There was a drop in death rates from breast cancer but the researchers attributed the decrease to medical advances. Overall, breast cancer screenings lead to more false diagnoses, which can be harmful. Mammograms do catch tumors earlier, when they’re still small, but current cancer treatments are effective even when tumors are detected late. Screenings may still have their place, especially for older women with a family history of breast cancer, but the research team argues that they’re unnecessary for most people.

The researchers’ findings suggest that mammograms may not be helpful for the average woman. Unless a woman is at a high risk of developing breast cancer, the screenings may cause harm by leading to misdiagnoses. Most of the tumors detected in mammograms are small and benign, requiring no treatment. The team cautions that these screenings still have value but shouldn’t be encouraged as part of a yearly health exam for young, low risk women.


Welch et al. Breast-Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness. New England Journal of Medicine (2016).

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