Preventing Cancer, by Elizabeth Whelan, New York: W.W. Norton, 1980, 285 pp., $9.95.
Out of a hundred diseases, fifty are caused by our own faults, forty by our carelessness.
quoted on the frontispiece
Yes, this may apply to the hundred diseases that we call "cancer," according to Elizabeth Whelan's splendid book. The central message is that you are not only most responsible for your own health but are also the central agent in preventing cancer in your own body. Her claim is that, "by following the advice in this book, you will, on the average, reduce your chances of developing cancer by some 20 to 50 percent or more."
Whelan, a researcher at the Harvard School of Public Health and director of the American Council on Science and Health, qualifies this claim by noting the obvious—that the potential benefit to a young person is much greater than that to a 60-year-old with a 40-year history of smoking two packs a day. This latter sad example already has a statistical probability of more than 50 percent of having a tumor growing in his lung and upper air and food passages or in his bladder or of having crippling emphysema or heart disease. Nevertheless, even such an individual can benefit from a change in habits. For example, a recent study has shown that in one type of lung cancer, patients who stop smoking live longer than those who continue to smoke.
Most of Whelan's book is occupied with specific discussions of factors known to increase the chance of developing cancer and some "much-talked-about factors which have never been shown to increase your odds on developing cancer." The proven risk factors include:
certain dietary influences
excessive alcohol consumption
exposure to excessive radiation
excessive sun exposure
certain drugs and hormones
poor sexual hygiene
The unproven risk factors include:
"chemicals" and additives in food
The final portion of the book is a summary discussion with an attempt to put the specifics into a general perspective, some surprising recommendations for public policy, and several appendices with practical tips for quitting cigarettes, eating prudently, and recognizing cancer warning signals.
Let's get down to specifics: cigarette smoking is the most important cause of preventable cancers in the United States. It causes more than 90 percent of the lung cancers (an estimated 90,000 deaths this year) and is an important risk factor in cancers of the head and neck region, the esophagus and the pancreas, and the bladder. It is therefore involved in more than one quarter of the cancer deaths per year in the United States. Thus, if you can eliminate your cigarette habit early in life, you can reduce your cancer risk by 25 percent from this factor alone.
Maybe I can help you with some calculations. On average, the life expectancy of a one-pack-a-day smoker is about seven years less than that of a nonsmoker. If you divide the number of minutes in seven years by the number of cigarettes smoked in a 40-year habit (not unusual), the result is an estimate of life expectancy decreased per cigarette. It is a staggering 12 minutes lost per cigarette smoked! The crushing realization is that this is even more time than is spent "enjoying" the smoke.
Contrary to public misimpressions, there is not an epidemic of cancer. If lung cancer is not counted and cancer death rates are adjusted for the fact that the average age of our population is increasing, then the total death rate from cancer is decreasing. It is only the impact of the rapid increase of lung cancer in the past 40 years (since cigarettes became popular) that causes the overall total to be increasing (see graphs).
Diet may be the next most important factor in cancers. Whelan states that many epidemiologists now believe that as many as 50 percent of cancers in women and 30 percent in men are the result of an imprudent diet. The evidence for this comes largely from comparisons of rates of cancer of the breast, prostate, and colon, which are much higher in countries like the United States, Canada, and Denmark than in countries like Costa Rica, Bulgaria, and Japan. These latter countries, however, have much higher rates of stomach cancer. But the variations do not seem to be due to a genetic difference, for when Japanese people move to Hawaii or the mainland and adopt American habits and lifestyles, their cancer rates tend to change and become like ours.
So diet differences are a reasonable factor to investigate, and detailed comparisons have shown a correlation between colon, breast, and prostate cancer rates and the intake of fat, particularly animal fat. This is buttressed by some laboratory studies on animals, but Whelan is the first to admit that the evidence for the linkage between high-fat diet and cancer is still very "preliminary." It is nowhere near as firm as is the evidence for the link between cigarette smoking and lung cancer, for example.
The "fat-intake theory" has recently been brought into question, however, by the results of another epidemiology study of 691 cases of cancer over 24 years, in 5,209 people from Framingham, Massachusetts. In this group, men with high levels of cholesterol were found to have significantly fewer cancers than men with low cholesterol levels. The most spectacular finding was that men with very high serum cholesterol levels (over 280) had less than 10 percent the incidence of colon cancer found in men with very low levels (less than 190).
Since high cholesterol level is ostensibly associated with high fat intake, this new evidence seems to indirectly contradict the fat-intake theory. Please, dear reader, do not take this as a cue to drastically increase your intake of saturated fats. One of the possible interpretations of the Framingham study is that the very-high-cholesterol men may have developed fewer cancers because they were dying early of heart disease.
Do Whelan's arguments have implications for human affairs? I believe that they point in the direction of "medical individualism"—treating each person as the primary determinant of his or her own health, through behavior such as smoking, diet, alcohol, exercise, and adaptation to stress.
The alternative to medical individualism is "medical collectivism"—the idea that legislation, spending more tax money, and increasing government control of and involvement in medicine are useful ways of improving health. The events of the past 15 years, however, have shown that such measures can do a great deal to increase the prices and total costs of health "care" but not very much to improve the status of health itself.
Simple-minded environmentalism is another variation of collectivist thinking about preventing cancer. Environmentalists have often obtained support for their proposals by exploiting cancer phobia in the public. As Whelan states, "It is now widely accepted that 70 to 90 percent of all human cancer is induced by environmental causes." And environmentalists repeat such statistics to support their cause. What they don't point out, though—and Whelan does—is that "environmental causes" here means any external factors, and not just "chemicals" in the air and water. In fact, the types of pollution that most people accept as truly environmental are described by Whelan as "factors which have never been shown to increase your odds on developing cancer."
What, then, can you do and not do to prevent cancer?
• Stop smoking cigarettes. If you cannot break your addiction, Whelan offers advice to decrease your risk: use only lowtar filter cigarettes; limit yourself to less than eight cigarettes daily; do not inhale deeply; discard cigarettes after smoking halfway; don't drink alcoholic beverages—alcohol seems to enhance the carcinogenic effect of tobacco.
• Don't expect government programs to save you. The "war on cancer" initiated by President Nixon and the National Cancer Institute has not been won. The major casualty has been the credibility of the oncology research community. The NCI asked the virologists, the immunologists, and the chemotherapists what was needed, and guess what their suggestions were? Of course, more money for research in virology, immunology, and new chemotherapy drugs. They discovered much more about what they didn't know than about how to cure or prevent cancer.
There have been dramatic advances in treatment effectiveness in childhood cancers and tumors affecting young adults. But cure rates generally creep upward at a few percent at a time, with few great "breakthroughs" like the increase in cures of localized Hodgkin's lymphoma from 10-20 percent in the '50s to 80-90 percent now, by the use of aggressive radiation therapy and multidrug chemotherapy.
• Abolish the Delaney clause. This 1958 amendment to the Food, Drug, and Cosmetic Act requires that any additive be banned if it is found to cause cancer in any experiment, in any animal, at any concentration. Whelan shows quite well that the clause, because of its absolutist and arbitrary approach to questions of great scientific complexity, does much more harm than good. It causes attention and funds to be poured into problems that have little medical importance, such as the minuscule risk from saccharin, and adds to cancer phobia in the public. If its philosophy were applied to oral contraceptives, the "pill" would have to be banned, because "all estrogens have carcinogenic properties" in some settings. Penicillin would also have to be banned, as it can cause cancer in some animals, although it has no known cancer-causing effect in humans. The net result is to remove effort from much more important tasks in cancer prevention.
• Read Preventing Cancer by Dr. Elizabeth Whelan. The book is well written and easy to understand, with clearly posed arguments and succinct useful tips on how to cut your personal risk by modifying your habits with respect to food, alcohol, sun exposure, sex, and drugs. Because some of the evidence on diet, etc., is still somewhat controversial, you may want to take some of the advice "with a grain of salt," but it will serve you well to be informed of current knowledge as new controversies erupt and new scare stories are trumpeted in the news.
Since there is no other book like this, Whelan's contribution, in terms of potential cancers prevented and lives saved, is immense. I salute her for writing a book that matters.
Howard Maccabee is a radiation oncology specialist who switched from nuclear engineering to medicine and recently established a private practice in northern California.