Part 1. The Bottom Line
We begin this book with our bottom line, because we think the advice of Sara Jeannette Duncan is good: "If you have anything of importance to tell me, please, please begin at the end!" So here is our conclusion:
Breast-cancer is a largely preventable disease, and we reach that good news because of our finding that a large share of recent and current breast-cancer in the United States is certainly due to past medical irradiation of the breasts with x-rays --- at all ages, including infancy and childhood. Much of today's radiation dosage is preventable, without any interference with necessary diagnostic radiology, and hence many future breast-cancers need not occur.
What do we mean by "a large share" of recent and current breast-cancer?
Our estimate is that about three-quarters of the current annual incidence of breast-cancer in the United States is being caused by earlier ionizing radiation, primarily from medical sources. We will show that the recently growing incidence is not mysterious, and that if we wish to understand why the incidence has been growing, we must look to radiation events in the life of women 15-25-35-45 and more years before breast-cancer diagnosis. Moreover, there is recent evidence about induction of early-onset breast-cancer by radiation (Chapter 3).
There are many stories in this book, but no villains. The cast of historical characters is interesting, impassioned, and sometimes very wise.
No one meant to do any harm. On the contrary. After discovery of the x-ray in 1895 and of radium in 1898, radiation was tried out widely in medicine, right up to recent times, in the hope of relieving a great variety of human afflictions. Some radiation therapies were (and are) clearly effective (and this book is highly complimentary about such uses). Some other therapies, clearly not effective, have been discontinued. But usefulness is not always clear-cut in medicine. For example, users reported benefits which others could not see, regarding one type of x-ray therapy which was used for infants and children from 1911 to almost 1960.
The finding of this book constitutes an example of what can happen from exposing people to new agents, such as x-rays, when no one knows the long-term consequences. Readers will see the innocent enthusiasm, the repeated assurances that the procedures were safe, and the power of the "technological imperative" to suppress the idea that there might be a problem with anything as wondrous and potentially useful as x-rays. This is a story of "disaster creep" --- a massive problem creeping up on society without any recognition.
In science, every important discovery should be challenged and checked by others, and our finding certainly will be. We will welcome the genuine, thoughtful critiques. And we expect our finding to be validated. We arrive at our startling conclusion after underestimating the past dosage of x-rays, and after using conversion-factors (conversion from dose to subsequent cancers) which derive from real-world observations. There is just no doubt that past radiation exposure accounts for a major share of our recent and current breast-cancer problem. The evidence for our finding is overwhelming --- if one simply looks.
Many will look thoughtfully at the input to this study --- but there will be exceptions. We expect our finding to be automatically rejected by some who merely want it to be faulty --- and who will comment upon it without even reading this book.
If breasts could talk, they might say, "Read first, judge second, and please start now!"Part 2. For Whom Is This Book Intended?
This book is intended for anyone interested in breast-cancer, and its prevention. Interest in the problem is the only requirement. The book is for medical professionals and for individuals with the greatest personal concern: Women in general --- and their families. Readers do not need to know every medical term in the stories, because the meaning of the stories will be clear anyway. No medical skill or knowledge is essential to understand what will be presented.
Many chapters will begin with a description of what happened, and will end with specific calculations based on the events. Of course, many readers will skip the numbers. The "easy readers" should feel no guilt for skipping the latter part of various chapters. Lots of professionals, also, read scientific journals without ever examining the calculations and tables there. But numbers are in journals, and also in this book, for a very important reason: To allow people to check for themselves exactly how the quantitative conclusions were reached, and to evaluate the validity for themselves.Part 3. An Astonishing Statement in a Fund-Raising Appeal
I've recently received in the mail a request for funds to help breast-cancer research. It said: "Breast cancer is the most commonly diagnosed cancer in American women today. It is the leading cause of death among women ages 40 to 44, and the leading cause of cancer death in women 20 to 54." No argument about that. Every part of that statement makes it all the more important for women to know precisely why we say that breast-cancer is largely preventable. Then the letter added:
"What's worse, even the best doctors have no idea what causes breast cancer or how to cure it." Cure is indeed problematical, and when successful, the process itself can be highly unpleasant. All the more reason why prevention is so very important.
But how can anyone in 1994 say that "even the best doctors have no idea what causes breast cancer"? This error also went out over NBC national news during October 1994, in the television network's coverage of Breast-Cancer Month. In reality, medical science has clearly known for some 20 years already that ionizing radiation is a prominent and proven cause of breast-cancer. Ionizing radiations include x-rays and gamma rays, as well as beta, alpha, and some other high-speed particles. (Radium is used in medicine as a source of powerful gamma rays.)
We think "the best doctors" do indeed know about the role of ionizing radiation as a prominent, proven cause of breast-cancer, but it is astonishing that both lay and medical sources commonly fail to mention this outstanding fact of medical science: Past medical exposure to ionizing radiation, 10, 20, 30, 40, and more years back in a woman's life, can cause breast-cancer.
Radiation exposure in the first few months of life may be the most serious in causation of later breast-cancer. In fact, irradiation of the breasts between age 0 (newborn) and age 9-years may cause many-fold more cases of breast-cancer, over the subsequent lifetime, than does irradiation of women over 40 years of age with the same amount (dose) of ionizing radiation.
The Current Size of the Problem, USA
Today, it is estimated that one woman out of every nine in the USA will develop breast-cancer sometime during her lifespan. The breast-cancer problem is reflected in the estimates below, of breast-cancer incidence in the USA (derived by the American Cancer Society from government data). The numbers exclude "in situ" cases. The rapidly rising numbers below reflect diagnosis, not death. As so many families know already, diagnosis in itself brings severe consequences, even if a woman dies of something else in the end. The numbers on the right show that the growth of the female population can explain only a small part of the rising incidence of breast-cancer. (The tabulation below is expanded in Tables 1 and 2, which are located after the final chapter.)
1970: 68,000 cases diagnosed; females of all ages = 104,309,000
1975: 88,000 cases diagnosed; females of all ages = 110,401,000 est.
1980: 108,000 cases diagnosed; females of all ages = 116,493,000
1985: 119,000 cases diagnosed; females of all ages = 122,474,500 est.
1990: 150,000 cases diagnosed; females of all ages = 128,454,000
1994: 182,000 cases diagnosed; females of all ages = 133,194,000Part 4. How Do We Know that Radiation Is a Cause of Breast-Cancer?
Every once in a while, a massive step forward in medicine is taken by the oldest technique in medical practice --- the careful taking by a physician of a patient's medical history. Such an event of landmark proportions is represented by the observations of Dr. Ian MacKenzie, a physician in Nova Scotia, Canada.
In 1961, a woman with a rapidly growing breast-cancer came to his office. He noticed that her cancer had occurred in the upper inner quadrant of her right breast, and that her skin over the right chest wall, breast, and sternum showed signs of dermatitis (skin inflammation).
MacKenzie questioned her carefully about her history, and learned that she had been treated 14-15 years earlier for pulmonary (lung) tuberculosis. In those years, a common practice was to let one of the lungs rest, by collapsing it with an injection of air between the chest wall and the lung. This procedure was called artificial pneumothorax therapy, and in her case, it took place over 46 months. Each time she had a re-fill of air into the chest, the status of the lung was checked with fluoroscopy, before and usually after.
Fluoroscopy is also called roentgenoscopy, in honor of Wilhelm Konrad Roentgen, who discovered x-rays in 1895. In roentgenoscopy, examination of a patient with x-rays takes place while the x-ray beam stays "on," so that the physician can observe what happens when the patient or the patient's organs are in motion. Roentgenoscopy is thus very different from roentgenography, which is the use of x-rays to expose a sheet of film (or other types of image-receivers) to produce the usual x-ray picture. Roentgenoscopy, requiring no development of film, produces information immediately.
When Dr. MacKenzie obtained his patient's sanitarium records, he learned that she had had at least 200 fluoroscopic examinations during her treatment. The patient remembered that her skin changes began during this period, too. Dr. MacKenzie recognized that she had radiation dermatitis, and he began to suspect that breast exposure to x-rays might also account for her breast-cancer.
To check on this idea, Dr. MacKenzie studied almost 800 women who had been treated for tuberculosis in one sanitarium during 1940-1949. The startling results were published in 1965. Of 510 women who did not receive artificial pneumothorax treatment and therefore did not have repeated fluoroscopies, one woman had subsequently developed breast-cancer by the time of Dr. MacKenzie's study. This is a rate of (1 woman / 510 women), or 0.00196. Of 271 women who did receive artificial pneumothorax treatment with multiple fluoroscopies, 13 had developed breast-cancer by the time of Dr. MacKenzie's study. This is a rate of (13 / 271), or 0.04797. The breast-cancer rate in the irradiated group was (0.04797 / 0.00196), or 24.5 times the rate in the non-irradiated group. In his paper (p.7), Dr. MacKenzie said:
"From the evidence presented, it would appear to be a reasonable conclusion that the well-recognized role played by ionizing radiation in the development of certain other forms of malignant disease can be extended to include carcinoma of the breast in the circumstances presented by these cases." If pulmonary tuberculosis itself were the cause of the breast-cancers, then the irradiated and non-irradiated cases should have had similar breast-cancer rates, as Dr. MacKenzie commented. Dr. MacKenzie's finding caused quite a "stir" in radiation circles.
1965 (March): Ian MacKenzie, "Breast Cancer Following Multiple Fluoroscopies," British Journal of Cancer 1965, Vol.19: 1-8.
Soon thereafter, C.K. Wanebo and colleagues, studying the survivors of the atomic bombings at Hiroshima and Nagasaki, and stimulated by the MacKenzie work, launched an investigation of breast-cancer in those survivors. In 1968, they published confirmatory evidence of human breast-cancer induction by ionizing radiation. In 1969, Myrden and Hiltz extended the follow-up time for MacKenzie's 1965 study. And in 1970, Arthur Tamplin and I used the MacKenzie and Wanebo data to quantify the dose-response for radiation-induced breast-cancer. We showed in The Lancet that the breast-cancer risk from ionizing radiation was quite serious indeed.
Proven, and Then Forgotten?
In the years which have followed MacKenzie's 1965 paper, numerous studies have confirmed and quantified the induction of breast-cancer by ionizing radiation. For the convenience of readers, we have identified a number of those papers by prominently flagging them with the symbol "#" in our list of references. Many of these studies have been analysed in Gofman 1981 and in Gofman 1990. In 1994, even further confirmation became available in the latest reports on cancer incidence in the A-Bomb Survivors (Mabuchi; Thompson; Tokunaga).
The radiation-causation of human breast-cancer is not in dispute. Nonetheless, it is commonly forgotten in discussions about the alleged mystery of breast-cancer causation.Part 5. What about Other Potential Causes of Breast Cancer?
Cancer --- not breast-cancer alone --- is now considered to be a genetic disease. It is thought that a tumor develops in stages from a single cell, as the cell and some of its descendants accumulate a set of several "genetic lesions." A lesion is an injury or loss of function. Genetic lesions are those which occur in the genetic molecules --- namely, in the DNA molecules which control a cell's proper operation, including the accuracy and appropriate rate of the cell's division. Genetic lesions in a cell can occur at any age.
Inherited diseases are properly called genetic diseases. They occur because offspring receive certain genetic lesions in the DNA which they inherit from their parents. (Mother and father do not often transmit the same lesions, however.) Inherited genetic lesions are present in the fertilized human egg. Since every cell we have is descended from the fertilized egg, the lesion is present in every cell. By contrast with an inherited lesion, a genetic lesion which occurs in childhood or adulthood is present only in the cell where it took place, and in cells descended from the altered cell, but it is not present as an all-cell lesion. So, inherited diseases are genetic, but not all genetic diseases have to be inherited. The responsible genetic lesions can occur after conception.
With respect to cancer, it is thought that cells become malignant only after they have accumulated several carcinogenic lesions (many estimates range from four to ten lesions). Some of the lesions may be inherited, and others may occur at any age after conception. Individuals who inherit one or more carcinogenic lesions in every cell, have an increased chance that some of their cells will accumulate a complete set of the necessary lesions during their lifetimes. Such people are born "predisposed" to develop full-blown, clinical cancer.
Interaction of Inheritance and "Other Forces"
Almost certainly, inherited carcinogenic lesions have a range from weak to strong. The famous lesions are the rare inherited ones which confer a high chance of cancer in a specific organ, with the clinical cancer often occurring at a very early age. We call those "destiny" lesions, and the weaker ones "predisposing" lesions.
The inherited "destiny" lesions are estimated to account for five to ten percent of human cancer. For breast-cancer, the estimate is about ten percent. Even a "destiny" lesion may need help from other forces, in order to create some cells with the complete set of genetic lesions required for full-blown cancer. By "other forces," we mean to include agents such as x-rays, viruses, or certain chemicals.
An inherited "predisposing" lesion, by definition, needs help from other forces in order to cause a cancer.
Do such other forces, acting in the absence of inherited carcinogenic lesions, ever produce the complete sets of lesions required for malignancy? At this time, there is no way to know how often this happens, if ever. It may turn out that cancer almost never develops in the absence of an inherited "head start" ... and almost always requires the interaction of inherited lesions with other forces.
The bottom line on inheritance and other forces is this:
A very large part of the cancer problem can be eliminated, if people correctly identify and eliminate the non-inherited forces which act alone or act in concert with inherited genetic lesions, in producing malignancy. This book shows that past exposure to medical x-rays is a major non-inherited cause of the breast-cancer which has occurred, is now occurring, and is already committed to occur in the future in the USA. Readers who follow the stories, chapter by chapter, will end up realizing that medical radiation is surely a non-inherited cause of other cancers, also. How large the share is, for other cancers, remains to be evaluated.
And What about Pesticides, Hormone Pills, Diet, and EMFs?
There is nothing about the finding of this book to imply that ionizing radiation is the only cause of recent breast-cancer.
Many non-inherited forces, including pesticide by-products, hormone pills, diet, exercise, EMFs (electro-magnetic fields and "transients"), and several additional factors, have been implicated by epidemiologic studies as potential contributors to recent rates of breast-cancer. (Epidemiology is a science which tries to find the causes of diseases, by comparing their frequencies in various groups of people.)
Do we dismiss these other forces? Not at all. Even agents and behaviors which cause no permanent genetic lesions may accelerate a developing cancer in several ways --- without casting any doubt upon the multi-step genetic model of cancer development. The power of such promoters may depend on the presence of genetic lesions.
Indeed, we take this opportunity to say that we are particularly concerned about the question of EMFs, to which human exposure is likely to increase in future years. We highly recommend a collection of papers on EMFs and breast-cancer (Slesin 1994).
With respect to ionizing radiation, the proof that extra exposure is a cause of cancer (including breast-cancer) comes from studies where all sorts of additional non-inherited causes may have been operating too. The point is this: In any valid epidemiologic study, those other carcinogens are acting equally upon the irradiated groups and upon the non-irradiated groups. Thus, the extra cancers in the irradiated groups can be attributed to the extra radiation, but the rest of the cancers are due to something else (such as equal exposure, on the average, of all the study-groups to chemicals, EMFs, or prior exposure to radiation-sources other than the source studied).
There is no inherent conflict or competition between carcinogens. The multi-step genetic model of cancer development "permits" contributions even to a single case of cancer, from heredity, ionizing radiation, viruses, and chemicals (for example). It is correct to say that each contributor caused the cancer, if the case would not have occurred when it did, without that contributor.
The finding of this book is that an estimated 75 percent of recent and current breast-cancer cases would not have occurred as they did, in the absence of earlier medical (and other) irradiation.
# # # # #