Are Screening Mammograms Advisable?

Are screening mammograms advisable? For accurate information let us turn to the Committee for Nuclear Responsibility and its excellent chairman, John William Gofman, MD, PhD. Gofman knows x-rays. Although he is Professor Emeritus of Molecular and Cell Biology, University of California at Berkeley, he started his career in the Manhattan Project, which developed the first atomic bomb. He shares patents on the fissionability of uranium-233 and on early processes for separating plutonium from fission products.

Gofman also led the team that discovered and characterized the lipoproteins (LDL and HDL), so important in the causation of heart disease. In 1963, he established the Biomedical Research Division for the Livermore National Laboratory, where he was in the forefront of research into the connection between chromosomal abnormalities and cancer. Gofman's work at Livermore resulted in his present "maverick" status, for when he warned the Atomic Energy Commission of how easily radiation could cause cancer, he suddenly was stripped of his major research grants. In recent years, as chairman of the Committee for Nuclear Responsibility, he has tried to warn the public and the medical profession of the danger of too-large doses of radiation used in diagnostic x-rays.

For an overview of the potential risks of ionizing radiation, I would suggest you look at the Committee’s website, and in particular Dr. Gofman’s penetrating article on making decisions regarding diagnostic x-rays: http://www.ratical.org/radiation/CNR/XHP/MPDaXrayST.html#Part1

The Potential Danger of Mammograms

Mammography can be used either to diagnose a known condition or, more commonly, to screen a general population that has no signs or symptoms of disease. There is little argument that screening mammography does sometimes detect small tumors that cannot normally be detected by manual breast examination. For this reason, screening mammography has become a bedrock of public health policy. There are posters and brochures in nearly every hospital and doctor's office. From TV ads and billboards to airport exhibits and public service announcements, the necessity of screening mammography is communicated through every possible media outlet.

But there have always been dissenters. I myself raised some doubts about it in my 1980 book, The Cancer Industry. Lately, as the result of a rigorous study from Scandinavia, there has been debate in the media over the safety, efficacy and advisability of mammograms. In the face of this uncertainty, many experts are calling on women to decide for themselves whether to have mammograms or not. "It is the women who will have to live with the consequences of their decisions," wrote the New York Times (April 14, 2002).

There is something ironic in this call by experts for women to decide for themselves. I’m all for patient empowerment. But for 25 years, these same experts insisted that they knew best and that screening mammograms were the way to catch breast cancer in its early "curable" stages. Now, they suddenly reveal themselves to be in a hopeless muddle. It is as if a group of trusting passengers boarded a ferry that advertised a quick and safe passage to the opposite shore, but mid-voyage, a thick fog developed, the radar failed, and the crew started to fight over the proper direction. And so the captain announced that the passengers would now have to decide for themselves on the proper course forward.

Since we have been set adrift, so to speak, by the experts, we should try to analyze the situation as logically as possible. First we need to ask, "Is there a potential harm in mammography?" After all, if mammograms were without any potential harm, there would be little to lose in undergoing them. But mammograms are a form of x-rays. And this fact alone should make us wary. Admittedly, the radiation dose of a mammogram has decreased dramatically over the years. But it still represents a potential risk. If we assume, says Dr. Gofman, that the total dose to the breast of a two-view mammogram is 0.2 rad, a woman who begins undergoing annual mammograms at age 50 will have, at age 65, a 1-in-500 risk of a fatal mammogram-induced breast cancer.

This is a relatively small risk, particularly if many lives are being saved at the same time. However, women may get more radiation than this. The upper permissible limit per exam has been 0.6 rad. For women receiving that much radiation, the risk would be three times higher. There are also certain women who carry genes that impair their ability to repair x-ray damage. They are in even greater danger. This does not take into account the risk from exposure to improperly calibrated machines and inept technicians.

"Even so," says Dr. Gofman, "it is reasonable to think that, from annual screening, your chance of not developing a mammogram-induced fatal breast cancer greatly exceeds the chance that you will."

However, there are other factors to consider. There is the possibility of a false-positive result. This is a suggestion, based on an ambiguous mammogram, that you may have breast cancer, when this cannot be confirmed by repeated tests. According to a study in the New England Journal of Medicine, the cumulative risk of a false-positive after ten exams ranges from 47 to 56 percent, depending on one’s age. And the more risk factors a woman has, the greater the chance of a false-positive reading.

The harm of a false-positive includes considerable anxiety, and additional exposure to x-rays and biopsies. Having been through this three times with my wife I can tell you it is a scarring experience, both physically and emotionally.

But worse yet is the possibility of overdiagnosis, in which mammography identifies "cancers" that are not true malignancies. Overdiagnosis inevitably leads to overtreatment using surgery, radiation and/or chemotherapy. No one knows how often this occurs, but it is often enough to worry Dr. Barnett Kramer, director of the Office of Disease Prevention at the National Institutes of Health (NIH). He told the New York Times that if screening worked perfectly, every breast cancer found early would correspond to one fewer cancer found later. That, he said, did not happen. "Mammography, instead, has resulted in a huge new population of women with early stage cancer but without a corresponding decline in the numbers of women with advanced cancer." In other words, a new category of "cancer" has been discovered, which would never have progressed to true malignancy if it was simply left alone.

An ironic side effect of overdiagnosis is that it causes the death rate from breast cancer to appear to decline, since doctors are now "curing" some "cancers" that would never have been fatal in the first place. "Perhaps," says Dr. Gofman, "future evidence will be able to settle the question: Does the USA recently have a large increase in the number of genuine breast cancers detected and successfully treated, or do we have a large number of non-cancers which are mistakenly identified as cancers and treated ‘successfully’? Which one is more likely?"

A Garden of My Own

I recently came across some of my earliest writings, a cache of postcards that I sent my parents from summer camp. They are not works of literary genius, but they do reveal my early interest in gardening. Although I lived most of my life in apartments, I always grabbed a chance to have a little garden. Now that I've moved to a house in the country, I am busy cultivating the garden I've dreamed of for fifty years.

God Almighty planted a garden, wrote Francis Bacon in 1601, "and indeed it is the purest of human pleasures. It is the greatest refreshment to the spirits of man." I agree. Getting up early and walking quietly in my garden before the day begins is one of my pleasures. My attachment to gardening is almost mystical.

What am I planting these days? I have put in two 40-foot rows of red raspberries. I have bound them in with coated wire, so that "they grow not out of course," as Bacon proposed. My grandchildren are feasting on them right now. I have a large patch of asparagus, and though it is too early to eat, it holds great potential for the coming years. And I have an assortment of vegetables, including various kinds of tomatoes, lettuce, peas, squash, eggplant, and two raised beds devoted entirely to garlic.

Pictured Below: Peas in Ralph's Garden

My wife and I started most of these from seed under our Gro-Lites in the spring. I built raised beds for the vegetables, but the planting is still helter-skelter. Perhaps next year I’ll get my act together.

What does this have to do with cancer? You might be surprised. Each year, we learn more about the anticancer properties of antioxidants in such foods as raspberries, garlic, onions and blueberries (we are within walking distance of an abandoned field). Gardening is also good for the soul. It brings on a meditative state, a feeling of unity with nature that can counteract the isolation and devastation of cancer and its treatment. And that's a valuable prescription for young and old alike.

--Ralph W. Moss, Ph.D.

FOOTNOTES

Cancer screening and the individual. New York Times editorial, Apr. 14, 2002, sect. 4, p. 12.

Elmore JG et al. Ten-year risk of false positive screening mammograms and clinical breast examinations. New Engl J Med 1998;338:1089-96.

Kolata G. Test proves fruitless, fueling new debate on cancer screening. New York Times, Science Times, Apr. 9, 2002, pp. D1+D4.

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