I just recently became aware of a 2014 report on a 25-year study involving almost 90,000 Canadian women to determine the benefits of mammograms. The researchers wanted to know if there was any advantage to finding breast cancers when they were too small to feel. The answer was no.
They also found that screening with mammograms can be harmful. One in five cancers found with mammography was not a threat to a woman’s health, yet the women received unnecessary chemotherapy, surgery, and/or radiation.
Approximately half the women were assigned to have regular breast exams by trained nurses, and half were given regular mammograms in addition to the breast exams.
At the end of the lengthy study, the number of women who died from breast cancer was 500 among those who had mammograms, and 505 among those who did not.
A quote from a NY Times article about the study: “Many cancers, researchers now recognize, grow slowly, or not at all, and do not require treatment. Some cancers even shrink or disappear on their own. But once cancer is detected, it is impossible to know if it is dangerous, so doctors treat them all.”
This reminds me of something I once read about prostate cancer—that it’s unwise for men to be screened at too early an age because screening is likely to pick up cancers that will grow so slowly that they’ll never become a problem.
In Switzerland, the Swiss Medical Board has advised that no new mammography programs be started, and that those already existing be limited in duration. One member of the Board said mammograms were not reducing the death rate from the disease, and they led to false positives and needless biopsies.
Mammograms are big money-makers. In the U.S., about 37 million mammograms are performed annually at a cost of about $100 per mammogram. I guess it’s not surprising that although the results of the Canadian study came out last year, mammograms are still promoted in the U.S. as far as I can tell.
In discussing the potential harm done by mammograms, I have to mention radiation. My only known risk of breast cancer is from having my adenoids removed via radiation when I was 6 years old. It has never made sense to me to expose myself to more of it, so I’ve had only two mammograms in my lifetime.
Another quote, this one from Dr. Russell P. Harris, a screen expert and professor of medicine at the University of North Carolina at Chapel Hill: “The decision to have a mammogram should not be a slam dunk.”