Breast Cancer: Are Yearly Mammograms Worthwhile?
Does Early Detection Save Lives?
Researchers also looked at whether or not early detection with mammograms was saving lives.
Over the period of the study, death rates from breast cancer in women 40 years or older dropped by 28%, a substantial decline.
But breast cancer death rates dropped even more (42%) among women under age 40, a group that doesn’t routinely get screening mammograms.
“We are left to conclude, as others have, that the good news in breast cancer -- decreasing mortality -- must largely be the result of improved treatment, not screening,” the researchers write.
This isn’t the first study to flag the harms of overdiagnosis tied to mammograms. Ten other studies conducted in Europe and Australia have estimated that somewhere between 10% and 47% of all breast cancers detected in those countries are unnecessarily treated.
Certain cautions apply.
The first is that it’s not possible to directly count cases of overdiagnosis. Studies that try to have to rely on estimates. Those estimates are always subject to errors and biases.
The second caveat is that the study results don’t apply to everyone.
Women at higher risk of cancer because they have a family history or because they carry genes for the disease “really have nothing to do with this,” Bleyer says. “They are in a completely different category and they do need to be detected as early as possible, because they get a worse kind of cancer and they get it earlier in life.”
Women at average risk should carefully weigh the benefits of mammograms against their harms, which include worry, further testing, and sometimes needless treatment.
“We strongly endorse the concept that women and their health professionals have conversations about these issues and come to the conclusion that’s right for them,” Lichtenfeld says.