What Causes Breast Cancer?

by Peter Montague

Breast cancer kills 46,000 women in the U.S. each year. On average, each of these women has her life cut short by 20 years, for a total loss of about a million person-years of productive life each year. Of course this huge cost to society is heaped on even greater burdens, the personal anguish and suffering, the motherless children, the shattered families.

The medical establishment dominated by male doctors pretends that the breast cancer epidemic will one day be reversed by some miracle cure, which we have now been promised for 50 years. Until that miracle arrives, we are told, there is nothing to be done except slice off women's breasts, pump their bodies full of toxic chemicals to kill cancer cells, burn them with radiation, and bury our dead. Meanwhile, the normal public health approach primary prevention languishes without mention and without funding. We know what causes the vast majority of cancers: exposure to carcinogens. What would a normal public health approach entail? Reduce the burden of cancer by reducing our exposure to carcinogens. One key idea has defined public health for more than 100 years: PREVENTION. But with cancer, everything is different. In the case of cancer, prevention has been banished from polite discussion.

Now a new, fully-documented book[1], by physician Janette D. Sherman, poses a fundamental challenge to all the doctors and researchers and health bureaucrats who have turned their backs on cancer prevention: "If cancers are not caused by chemicals, endocrine-disrupting chemicals, and ionizing radiation, what are the causes? How else can one explain the doubling, since 1940, of a woman's likelihood of developing breast cancer, increasing in tandem with prostate and childhood cancers?," Dr. Sherman asks.(pg. x) And if exposures are the problem, then ending exposures is the solution: "Actual prevention means eliminating factors that cause cancer in the first place."(pg. 31)

Dr. Sherman is a practicing physician who has treated 8000 patients over 30 years. Unlike most physicians, she possesses an extensive knowledge of chemistry. Furthermore, she has become a historian by examining a large body of medical and public health literature dating back to the 19th century. It is this unique combination -- of historical view, knowledge of chemistry, deep personal experience as a physician, and an ethical clarity that PRIMARY PREVENTION is the proper policy -- that makes this book important and compelling.

The book begins with two chapters emphasizing the similarities among all living things that are made up of cells including humans, animals and plants. Cells in every creature can go awry and start to grow uncontrollably, a definition of cancer. Because all cell-based creatures are so similar, what we learn from one can often tell us something useful about another. For example, when we learn from the Smithsonian Institution that sharks get cancer from swimming in waters contaminated with industrial chemicals, we learn (or SHOULD learn) something useful about our own vulnerability to exotic chemicals.(pg. 9)

Turning to breast cancer, Dr. Sherman lists the known "risk factors" the common characteristics shared by many women who get breast cancer: early menarche (age at which menstruation begins); late menopause (age at which menstruation ends); late childbirth and the birth of few or no children; no experience breast-feeding; obesity; high fat diet; being tall; having cancer of the ovaries or uterus; use of oral contraceptives; excessive use of alcohol.

"What is the message running through all of these 'risks?'" Dr. Sherman asks. "Hormones, hormones, and hormones. Hormones of the wrong kind, hormones too soon in a girl's life, hormones for too many years in a woman's life, too many chemicals with hormonal action, and too great a total hormonal load."(pg. 20)

Dr. Sherman then turns her focus to the one fully-established cause of breast (and other) cancers: ionizing radiation, from x-rays, and from nuclear power plant emissions and the radioactive fallout from A-bomb tests.

These, then, are the environmental factors that give rise to breast cancer: exposures to cancer-causing chemicals, to hormonally-active chemicals, and to ionizing radiation in air, food and water. How do we know the environment air, food, water and ionizing radiation plays an important role in causing breast cancer? Because when Asian women move from their homelands to the U.S., their breast cancer rate soars. There is something in the environment of the U.S. (and other western industrial countries) causing an epidemic of this hormone-related disease. The medical research establishment likes to call it "lifestyle factors" but it's really environment. Air, food, water, ionizing radiation.

With this basic information in hand, Dr. Sherman then describes historically and today the exposure of women in the U.S. to a flood of carcinogenic and hormonally active chemicals, plus ionizing radiation.

Take common pharmaceutical products, for example. Canadian researchers have demonstrated enhanced cancer growth in mice given daily HUMAN-EQUIVALENT doses of three commonly-used antihistamines, which are sold under the trade names Claritin, Histamil and Atarax.(pg. 21) Two years earlier the same researchers had reported breast cancer promotion in rodents fed clinically-relevant doses of antidepressant drugs, which are marketed as Elavil and Prozac.(pg. 21) Millions of women in the U.S. are taking these drugs today.

At least 5 million women in the U.S. are currently taking Premarin the most often-prescribed form of estrogen (female sex hormone), to ease the transition through menopause.(pg. 156) This is called "hormone replacement therapy" and it is routine, recommended medical practice in the U.S. A review of 51 studies of women taking hormone replacement therapy showed that those who never took hormones had a breast cancer rate ranging from 18 to 63 per 1000 women. Those who took hormones for five years experienced an additional 2 breast cancers per 1000 women; after 10 years of hormone therapy the additional breast cancers rose to 6 per 1000. The danger largely disappears 5 years after discontinuing use.

Hormones are big business. Despite evidence that synthetic hormones caused cancer in rodents and rabbits, American drug companies began selling synthetic hormones in 1934 in cosmetics, drugs, food additives, and animal feed. The best-known is DES (diethylstilbestrol) but there were and still are many others. The National Cancer Institute (NCI) in 1938 published a study showing that DES caused breast cancer in rodents. Three years later, in 1941, NCI published a second study confirming that DES caused breast cancer in rodents. That year the U.S. Food and Drug Administration (FDA) approved DES for commercial use in women.(pg. 91)

DES is 400 times as potent as natural estrogen and can be made for pennies per pill. It was therefore phenomenally profitable and researchers aggressively sought new uses. DES soon was being used to prevent miscarriages, as a "morning after" pill to prevent pregnancies, and as a breast-enlargement cream. It wasn't long before researchers discovered that they could make chickens, cows and pigs grow faster if they fed them hormones, and a huge new market for hormones opened up. As early as 1947, a hormonal effect was reported among U.S. women who ate chicken treated with growth hormones. (Chapter 7, note 55.) Between 1954 and 1973 three quarters of all beef cattle slaughtered in the U.S. grew fat on DES.

In 1971, human cancer from DES exposure was confirmed and in 1973 DES was banned from meat, so other growth hormones were substituted. Most recently, of course, the U.S. FDA has allowed the U.S. milk supply to be modified to increase the levels of a growth hormone (called IGF-1) known to stimulate growth of breast cells in women. (pg. 101)

Still today most U.S. beef, chickens and pigs are intentionally contaminated with growth hormones which is why Europeans refuse to allow the import of U.S. beef. European scientists are asking the same question that Dr. Sherman raises: "[H]ormones are administered to meat animals to promote growth and weight gain. Why should humans expect to not respond similarly to such chemical stimuli?"(pgs. 16-17)

Then of course there are dozens probably, in fact, hundreds of household chemicals and industrial byproducts that are hormonally active: pesticides, cleansers, solvents, plasticizers, surfactants, dyes, cosmetics, PCBs, dioxins, and so forth, that interfere with, or mimic, naturally-occurring hormones. We are awash in these, at low levels, from conception until death. See www.ourstolenfuture.org.

How many growth-stimulating and cancer-promoting hormones can we ingest or absorb through our lungs and skin before we feel the effects? No one in authority is asking that crucial question, but Janette Sherman is asking it, pointedly, and armed to the teeth with scientific evidence.

Then there is radioactivity. In 1984, a study of Mormon families in Utah downwind from the nuclear tests in Nevada reported elevated numbers of breast cancers.(pg. 65) Girls who survived the bombing of Hiroshima are now dying in excessive numbers from breast cancer. Dr. John Gofman has reviewed 22 separate studies confirming unequivocally that exposure to ionizing radiation causes breast cancer. (See REHN #693.) Janette Sherman does a good job of summarizing ecological studies showing that women living near nuclear power plants suffer from elevated numbers of breast cancers. These studies, by their nature, are suggestive and not conclusive. but there is ample reason to believe that all nuclear power plants leak radioactivity routinely into local air and water and that any exposure to ionizing radiation increases a woman's danger of breast cancer. The only way to PREVENT this problem is to end nuclear power permanently.

Why has the U.S. turned its back on the preventive approach to cancer? Dr. Sherman returns to this question throughout her book. For example, in a devastating chapter on Tamoxifen (a known cancer-causing chemical now approved by U.S. FDA for use in women), she asks, "Why is our primary well-funded National Cancer Institute not devoting its efforts to primary prevention? Has breast cancer, like so many aspects of our culture, become just another business opportunity?"(pg. 149)

In the end, Dr. Sherman reaches a conclusion about that question: "There is a massing, in a few hands, of the control of production, distribution and use of pharmaceutical drugs and appliances; control of the sale and use of medical and laboratory tests; the consolidation and control of hospitals, nursing homes, and home care providers. We are no longer people who become sick. We have become markets. Is it any wonder that prevention receives so little attention? Cancer is a big and successful business!" (pg. 207)

And, finally: "Reflecting on the purpose of the corporation to sell products and services and maximize profits, it becomes apparent that prevention cannot be in the interest of the bottom line. What a sad and bitter realization," she concludes.(pg. 228)

Despite this sad and bitter conclusion, this is a powerful upbeat book about what citizens can and must do to end the epidemic of cancer that is sweeping the western world. If the truth shall set us free, this book is an important part of our collective liberation, freeing us from the lies and deceptions, the false promises of cancer cures always "just around the corner." Cancer is caused by exposure to carcinogens. The way to solve the cancer problem is to prevent exposures. This means we must end nuclear power, and demand clean food, water and air. Janette Sherman's contribution has been to give us a wealth of powerful evidence on which to act. Now it is up to us.

[1] Janette D. Sherman, LIFE'S DELICATE BALANCE; THE CAUSES AND PREVENTION OF BREAST CANCER (New York and London: Taylor and Francis, 2000). ISBN 1-56032-870-3.


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