Mammograms can help–and harm

Opinion: Mammograms can help–and harm –

  • To understand why, you need to know how doctors now think about cancer: in terms of turtles, rabbits and birds. The goal is not to let any of the animals escape the barnyard pen to become deadly. But the turtles aren’t going anywhere anyway. They are the indolent, nonlethal cancers. The rabbits are ready to hop out at any time. They are the potentially lethal cancers, cancers that might be stopped by early detection and treatment. Then there are the birds. Quite simply, they are already gone. They are the most aggressive cancers, the ones that have already spread by the time they are detectable, the ones that are beyond cure.
  • all women contemplating mammography should understand the other possibilities.
  • One possibility is that it could not save a life
  • Yet in every trial of screening, some women die from breast cancer despite its being detected early.
  • The birds are the reason why the rate at which women present with metastatic breast cancer in the United States remains unchanged, despite three decades of widespread screening mammography.
  • Another possibility is that early detection was unnecessary — that she could have done just as well had her cancer progressed to the point she noticed a breast lump.
  • the bigger story in breast cancer is the dramatic improvement in treatment over the last 20 years. Ironically, the better we are at treating breast cancer — the less important it is to screen for it.
  • The final possibility is that she was overdiagnosed — diagnosed with a cancer that may not have been destined to ever bother her. Cancer biologists now recognize that small collections of abnormal cells may meet the pathological criteria for cancer, yet never progress to affect the patient. In other words, her cancer may have been a turtle: it may not have been going anywhere anyway.
  • women are three times more likely to be overdiagnosed than they are to have their “life saved.”
  • But most agree overdiagnosis is more common than having your life saved
  • That nuance is lost in the powerful survivor stories that appear regularly in the media.
  • Unfortunately, the more likely interpretation is that they represent evidence of harm

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