Mammograms - benefits may not outweigh the risks

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In 2002, Danish scientists shocked the world of medicine by suggesting that their research did not back up the theory that mammograms helped protect women from dying of breast cancer.  Before this no one had questioned the yearly mammogram, still advocated by many medical providers except those proponents of alternative medicine like Dr William Campbell Douglas who produces an email called the "Daily Dose". In one of his articles, Dr Campbell, in 2004, suggested that mammograms might actually increase the risk of cancer, reminding his readers that he had repeatedly warned about the dangers of mammograms.  He cited a 1992 epidemiological study of 90,000 women, in Canada which suggested that women having regular mammograms showed a significant increase (36%-52%) in mortality from breast cancer.

An article by two Danish researchers, Dr. Peter Gotzsche, and Ole Olsen, of the Nordic Cochrane Center in Copenhagen, published in the October 20th 2002 issue of The Lancet, challenged assumptions about mammograms, calling previous studies "flawed."   The scientists analyzed seven major studies which "proved" that women having regular mammograms had a lower risk of dying of breast cancer (note: these are the studies often cited by the American Cancer Society in advocating mammograms). The studies, Gotzsche and Olson concluded, did not meet the requirements of scientific standards and were unreliable.

Gotzsche and Olsen found that:

* While it is often asserted that early detection spares patients more aggressive treatments, screening results in over-diagnosis, which has led to a 20% increase in mastectomies and a 30% increase in the removal of tumors (tumorectomies).

* Mammograms not only pick up slow-growing tumors, but also identify cell changes that, under a microscope, look like cancer, but are biologically benign. As a result, doctors may have aggressively treated something that may have gone unnoticed during the women's lifetime.

Continuing research from Canada and Sweden and even the USA seems to back up Gotzsche and Olsen's results. They have suggested that women having mammograms regularly, had little to no lower risk of dying of breast cancer than did women only doing the nightly breast self exams.

An article appearing in the Journal of the American Medical Association, Oct 21, 2009, stated new research suggests that the number of early detections has not changed since mammograms became popular.

According to the abstract:

One possible explanation is that screening may be increasing the burden of low-risk cancers without significantly reducing the burden of more aggressively growing cancers and therefore not resulting in the anticipated reduction in cancer mortality.

This analysis by by Dr. Laura Esserman, a professor of surgery and radiology at the University of California, San Francisco, and director of the Carol Frank Buck Breast Care Center there, and Dr. Ian Thompson, professor and chairman of the department of urology at The University of Texas Health Science Center, San Antonio suggested that perhaps some very slow growing cancers or "pre cancers" do not need to be treated and that in cases like that, the risks of treatment may outweigh the benefits.

Finally another researcher suggested that fast growing breast cancers can pop up between mammograms (usually given at 1 year intervals) as the reason why for many women, the self breast exam works better.

And a growing body of evidence suggests that mammograms themselves may raise the risk of breast cancer since they deliver to each breast, 1000 times the amount of radiation delivered in a chest X-ray.

Additionally false positives from mammograms have been estimated as high as from 73 to 90 percent.  False positives require additional mammograms (another 1000 times the radiation of a chest x-ray to each breast) and often, surgical biopsies which can be invasive.  A family member has experienced 3 or 4 false positives and a friend of mine experienced a positive, got another mammogram and again got a positive and ended up with an invasive biopsy which took three months to heal. (She is 73, an age which some have questioned even need to get mammograms).  And of course, she did not have breast cancer.  It was a false positive the mammogram saw.  False positives not only lead to more mammograms which might increase the risk of breast cancer but also cause women a lot of psychological stress.

Because of the new data, U.S. Preventative Services Task Force issued new guidelines recommending against routine mammograms for women in their forties (in 2009).

Mammograms probably save some lives, most agree, but each person must decide whether the risks outweigh the benefits.  Right now, there seems not real good evidence that the breast self exam still isn't the best way of detecting breast cancer.

At one CME I attended, one of the physicians pointed out that perhaps mammograms were not as effective as first thought because when cancer became detectable in a mammogram, it would also be detectable in a breast self exam.

A physician quoted in one of the articles agreed.  Coming out clean (cancer free) on a mammogram, she went home, did a breast self exam and found a breast cancer.  Needless to say, she no longer recommends mammograms for her patients.


JAMA Oct 21, 2009 available on the web at

 Lancet Oct 2002 - Goesche / Olson metastudy - article in the New York Times, Oct 2002