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Reduce your risk of breast cancer: Avoid mammograms

Posted by medconsumers on July 14, 2009

Want to know the best way to cut your chances of becoming a breast cancer patient? Stop having screening mammograms. Sure, the researchers who recently published a five-country study in the British Medical Journal would never express their findings in this manner.  But read their results and decide for yourself.  And keep in mind, many breast cancers detected by mammography will not become deadly or even produce symptoms if left untreated.  Now it is known, one in three screening-detected breast cancers fit that description.

Two Danish researchers conducted a systematic review of the breast cancer incidence in the seven years before a mammography screening program was introduced and the seven years after the screening program had been in full swing. The women in this review began having mammograms at the age of 50 years in the United Kingdom, Manitoba, Canada, New South Wales, Australia, Sweden and parts of Norway. The researchers were looking specifically at the number of women diagnosed with breast cancer after mass screening began. Although they expected a lower breast cancer incidence among the women as they grew older, this was not the case.

Here is what the researchers concluded, based on women who began screening at age 50 years. For every 2,000 women who undergo regular mammography screening over the next ten years, one will avoid a breast cancer death; 10 women will be diagnosed with a non-lethal breast cancer and treated unnecessarily; 10 to 15 women will be told they have breast cancer earlier than they would otherwise have been told, though this will have no affect on their prognosis (i.e., whether a woman’s breast cancer is found on a mammogram at age 55 or she finds it herself at age 65, her destiny is unchanged); and 100 to 500 women will have at least one “false alarm” that in about half the cases leads to a biopsy.

This review was conducted by Karsten Juhl Jorgensen and Peter C. Gotzsche, MD, of the Nordic Cochrane Centre in Copenhagen. Both have written extensively on the topic of overdiagnosis, which they define as “the detection of cancers that will not cause death or symptoms.” There is no foolproof way to determine which mammography-detected cancers do not progress. Virtually all are treated as if they will.

The lead author, Dr. Jorgensen, was asked by e-mail whether it is reasonable for a woman to decide not to have screening mammograms as a means of reducing her chance of having breast cancer. “In the light of our estimates of overdiagnosis, I would say that we now have to consider mammography screening as a major risk factor for getting a breast cancer diagnosis. And a preventable one, too,” he responded. “Of course, the breast cancers overdiagnosed through screening differ from the symptomatic ones by being non-lethal, but the individual woman cannot know this and the remaining consequences are the same (the surgery, radiotherapy and psychological stress).”

This is not the first time mammography screening was shown to cause more harm than good. Overdiagnosis and overtreatment were first identified in a 2000 systematic review of all seven trials worldwide that had randomly assigned women to receive mammograms or not. That review, which originally appeared in the British journal Lancet, has been updated as a Cochrane review (see the Web site of the Nordic Cochrane Centre).

Safest course of action? Seek medical attention at the first sign of a breast symptom.

ADDENDUM: A 2010 study published in the New England Journal of Medicine lends support to this suggestion. See this New York Times report about the study, entitled “Mammograms’ value in cancer fight at issue.”

Note: after this article was written, a federal committee set new mammography screening guidelines for women under 50, read Mammogram Uproar.

Maryann Napoli, Center for Medical Consumers(c)

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One Response to “Reduce your risk of breast cancer: Avoid mammograms”

  1. Thank you, Maryann! This new research has broad implications on women’s health care, and yet, unless I missed it, the major media (and even minor media) did not pick up on this important study or story. I hope that your organization is able to fundraise to send out press releases to the major media on stories such as this. We need your wisdom spread more widely!

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