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1. O’Rourke RA and others. American College of Cardiology/ American Heart Association expert consensus document on electron-beam computed tomography for the diagnosis and prognosis of coronary artery disease. Circulation 102:126–140, 2000.

CanCer Suppose someone began marketing automobiles with claims that they can run on water. Most people would want this to be proven and guaran- teed or they would pass up the offer. Yet many people who feel desperate about a health problem are vulnerable to promises from individuals who . . . use methods that are unproven according to the criteria of the scientific community. This type of analogy might help patients place dubious cancer treatment in proper perspective. Helene Brown1 © 1980 stephen barrett, m.d. Chapter Sixteen Part Four Personal Health Concerns330 The term cancer encompasses more than 100 different diseases characterized by abnormal cell growth. The abnormal cells do not function usefully in the body and can destroy normal tissue. No single form of treatment is best for all types of cancer because each type of tumor has its own characteristics. Since cancer cells are quite similar to normal cells, it is not simple to kill the one while preserving the other. These concepts should be useful in understanding why any method proposed as effective against all cancers should be viewed with great skepticism. Cancer re- searchers do not expect to find such a “magic bullet” in the foreseeable future. Cancer ranks as the second leading cause of death in the United States. The American Cancer Society (ACS)2,3 estimated that in 2011 (a) about 572,000 million Americans would die of cancer, and (b) about 1.6 mil- lion new cases of invasive cancer would be discovered. These figures did not include about 2 million cases of superficial skin cancers that are easily diagnosed and treated or about 111,000 cases of cancers of the female breast or melanomas that are so small, localized (in situ), and curable that they are tabulated separately. About one out of four deaths in the United States is due to cancer. However, the overall age-adjusted cancer death rate has gradually decreased during the past 40 years. Both prevention activities and improvements in medical care have contributed to this decline. This chapter discusses the risk factors for can- cer, preventive measures, scientific (evidence-based) treatment methods, diet and cancer, susceptibility to quackery, questionable methods, consumer protection laws, and information sources. avoidable Causes of CanCer Cancer is the result of a complex interaction of causative agents, both environmental and genetic. The most com- mon direct cause of human cancer is tobacco smoking, which is responsible for 85% to 90% of lung cancer cases as well as cancers of the bladder, mouth, larynx, esopha- gus, pancreas, and possibly other organs.4 Other causes of cancer are related to excessive alcohol consumption, radiation, and certain sexual patterns, infections, drugs, and occupational exposures.5 The effect of diet on cancer is not clearly established. However, epidemiologic studies have found an associa- tion between low intakes of fruits and vegetables and increased incidence of certain cancers. Obesity has been linked to cancers of the colon/rectum, breast (postmeno- pausal), uterus, and kidney. Excessive intake of alcohol increases the risk for cancer of the esophagus, mouth, rectum, liver, and pos- sibly other sites. Smoking multiplies this risk at some sites.

• The most common avoidable cause of cancer is tobacco smoking.
• No evidence exists that food additives increase the risk of cancer in humans, but many naturally occurring food components do. If significant evidence existed that an additive is dangerous, the FDA would ban it.
• In contrast to the epidemiologic evidence on cigarette smoking and cancer, evidence for the influence of dietary factors and cancer is uncertain.
• Antioxidant supplements have not been proven to prevent cancer.
• Treatments promoted with simplistic notions about cancer or with testimonials should be disregarded.
• The National Cancer Institute’s computerized database provides physicians with up-to-date information about cancer treatment. This enables most cancer patients to benefit from current knowledge without having to travel far.

Keep These poinTs in Mind as You sTudY This ChapTer Key Concepts Warning Signals The American Cancer Society lists the following cancer warning signals as reasons to consult a physician.

• Change in bowel or bladder habits • A sore that does not heal • Unusual bleeding or discharge • Thickening or lump in breast or elsewhere • Indigestion or difficulty in swallowing • Obvious change in a wart or mole • Nagging cough or hoarseness

√ Consumer Tip Chapter Sixteen Cancer 331 High-dose exposure to ionizing radiation increases the chances of leukemia and skin cancer. Exposure to high indoor levels of radon increases the incidence of lung cancer, particularly among cigarette smokers. The Environmental Protection Agency recommends that homes with average radon levels of 4 picocuries per liter or greater undergo corrective measures. About 6% of homes in the United States have levels that high.6 Guidance is available from the National Safety Council’s Radon Fix-It Line (800-644-6999). Human papilloma virus (HPV) infection can cause genital warts, about 75% of cervical cancers, and several other types of cancer. The HPV vaccine can sharply re- duce the incidence of these cancers, but, for maximum effect, must be given before sexual activity begins. In the United States, more than 20 million people are infected and about 6 million get a new genital HPV infection each year. Gardasil is approved for preventing cervical, vaginal, and vulvar cancer in females 9 to 26 years old and for preventing genital warts in males 9 to 26 years old. Gardasil does not fully protect everyone or protect against diseases caused by other HPV types or against diseases not caused by HPV. It is given as 3 injections over 6 months. Proponents argue that the only way the vaccination can work as a public health measure is if it is widely used. Opponents claim that its use will endorse and en- courage teenage sexual activity, although no scientific data support that belief. There is also controversy about whether HPV vaccination should be mandated or offered on a voluntary basis.7 Chronic infections with HIV, hepatitis B, and Heli- cobacter pylori (the bacterium that causes peptic ulcers) are associated with increased incidence of other cancers. Ultraviolet rays cause the majority of skin cancers. The principal source is the sun, but indoor tanning de- vices are another source (see Chapter 18). High-dose, long-term exposure to a number of oc- cupational chemicals has been shown to increase the risk of cancer. These include benzene, asbestos used for insulating and fireproofing, and vinyl chloride used in the production of plastics. Despite the presence of carcinogenic substances in the atmosphere, there is no firm evidence that air pollution is a significant cause of cancer. Nor is there any credible evidence or reason to believe that living or working near electric power lines or using cell phones increases cancer risk.8,9 There is no evidence that food additives used in the United States increase the risk of any form of hu- man cancer. A 1996 National Research Council report10 concluded (a) cancer-causing chemicals that occur naturally in foods are far more numerous than synthetic carcinogens, yet both types are consumed at levels so low that they appear to pose little threat to human health; (b) although some chemicals in the diet have the ability to cause cancer, they appear to be a threat only when present in foods that form an unusually large part of the diet; (c) the varied and balanced diet needed for good nutrition seems to provide significant protection from the natural toxicants in our foods; and (d) the human diet contains a mixture of small amounts of thousands of chemicals, some that may cause cancer and some that may help prevent it by acting as anticarcinogens. The National Cancer Institute 11 has concluded that “there is no clear evidence that the artificial sweeteners available commercially in the United States are associated with cancer risk in humans.” prevenTive Measures Cancer prevention can take two forms: primary preven- tion (before it occurs) and secondary prevention (discov- ery before symptoms occur). The most important primary preventive measure—probably the most important health decision an individual can make—is to avoid cigarettes and other tobacco products. The American Cancer So- ciety’s dietary recommendations are discussed later in this chapter. Other important measures include regular exercise12 and avoidance of excessive alcohol intake and sun overexposure (see Chapter 18). Secondary prevention attempts to detect and treat cancer in its early stages in order to improve outcome. Secondary prevention measures include periodic physi- cal examinations, Pap smears, sigmoidoscopy, colonos- copy, mammography, and tests to detect blood in the stool. Chapter 5 contains guidelines for frequency of these examinations. Thermography (measuring heat given off by a part of the body) and transillumination (shining of red and near-infrared light through a body part to illuminate its inner structures) are not valid techniques for breast cancer detection. diagnosis Although cancer is often suspected because of a physical finding, laboratory test, or imaging procedure, standard practice requires confirmation through microscopic examination by a pathologist. Specimens usually are obtained by biopsy of a small piece of tissue suspected of being cancerous. Cancer diagnosis is sometimes difficult. Part Four Personal Health Concerns332 However, although the frequency of diagnostic errors is unknown, it appears low. prognosis Once a cancer is identified, the next steps are grading and staging. Grading classifies cancer cells in terms of how abnormal they look under a microscope and how quickly the tumor is likely to grow and spread.13 Stag- ing estimates how far the disease has advanced along its usual course.14 For most cancers this is based on the size of the primary tumor, the involvement of lymph nodes, and the presence of metastases (tumors that have spread to distant sites through the bloodstream or lymphatic channels). Grading and staging are used to help select appropriate treatment, estimate prognosis (probable course), and evaluate treatment results. The National Cancer Institute (NCI) estimates that about 68% of the people diagnosed with cancer are likely to live 5 years or more.3 Its data from 1999 through 2006 include the following 5-year survival rates by sites: uterus, 61% to 86%; larynx, 49% to 65%; breast, 78% to 91%; cervix, 64% to 73%; bladder, 66% to 82%; prostate, 97% to 100%; colon, 55% to 67%; and lung, 13% to 17%. (The lower numbers are for blacks; the higher ones are for whites.) For certain types of cancers that usually occur before age 45, treatment with anticancer drugs has produced a sharp fall in overall death rates and has resulted in long- term survival for many patients. These cancers include Hodgkin’s disease and acute childhood leukemia. The overall survival rates for most other cancers have risen slowly. The outlook for an individual with cancer depends on the type of tumor, its location, and the extent of its spread. Some tumors grow slowly and remain localized, whereas others grow rapidly and metastasize. Sponta- neous remission of certain cancers occurs, although rarely. Learning one’s prognosis can be complicated by the fact that many physicians are reluctant to com- municate bad news. Predictions are often expressed as median survival time, the point at which, for each tumor type and stage, about half the patients will be dead. Some patients think that a median survival time of six months means that they have six months to live. However, half will survive longer, and a few may survive much longer. Researchers who surveyed 13 prominent newspapers and magazines have concluded that (a) stories about can- cer often discuss aggressive treatment and survival but rarely discuss treatment failure, adverse events, end-of- life care, or death; (b) these portrayals may give patients an inappropriately optimistic view of cancer treatment, outcome, and prognosis; and (c) insufficient attention is paid to how palliative and hospice care compare with “heroic” attempts at cures.15 Goozner16 has observed that “Hopeful stories . . . increasingly come directly from the medical literature, which has a well-oiled machine for getting its most promising ‘breakthrough’ research into the nation’s premier newspapers and news magazines.” Patients with a poor prognosis often face a serious dilemma. In many cases, although surgery, radiation, or chemotherapy might briefly prolong life, the quality of that life (due to side effects or disability) would be so poor that further treatment is unwarranted. In some cases, measures that have been proven useful against one type of tumor may be inappropriately tried against another type. It is also important to realize that life-saving methods sometimes have permanent adverse effects. For these reasons, people with cancer should investigate their options thoroughly. evidenCe-based TreaTMenT MeThods The main types of standard treatment are surgery, radiation therapy, and chemotherapy. In some cases a combination is more effective than one method alone. Treatment may be done with the hope of curing the patient, or it may be done palliatively, with the hope of relieving discomfort or prolonging life. Even when it cannot increase survival time, modern cancer treatment may greatly improve the quality of life for patients with advanced cancers. Surgery is the primary treatment method for most major forms of cancer, especially in their early stages. Cancer surgery chiefly involves removal of the tumor and nearby tissues that may contain cancer cells. In some cases where the cancer has not spread, no further treatment is needed. Radiation therapy attacks cancers with ionizing radiation that is administered either externally with a machine or internally by inserting radioactive material into a body cavity or organ. Rapidly dividing cancer cells are particularly sensitive to radiation damage, but normal cells are also vulnerable. Radiation therapy thus involves a balance between destroying the cancer cells and the risk of side effects from damage to normal cells. Chemotherapy (treatment with anticancer drugs) has become increasingly effective. Because these drugs circulate to all parts of the body, they can attack cancer cells that have spread to distant organs. More than 100 Chapter Sixteen Cancer 333 drugs have been FDA-approved for fighting cancer, and many others are being tested experimentally. Curative dosages usually have severe side effects. Lesser doses may be appropriate for palliation. However, former NCI Director Vincent DeVita warned that giving lesser dos- ages to potentially curable patients is “throwing away the cure rate.”17 Some techniques are used to enhance the effective- ness of current methods. Photodynamic therapy (PDT) uses special drugs along with light to kill cancer cells. Localized hyperthermia uses heat to kill cancer cells or make other treatments more effective. Marrow trans- plants are used to repopulate the patient’s blood cells after chemotherapy. Other therapies use the body’s im- mune system to fight cancer or to lessen the side effects of other treatments. These modalities include interferons, interleukins, colony-stimulating factors, monoclonal antibodies, vaccines, gene therapy, and nonspecific im- munomodulating agents.18 Some are “targeted therapies” that use substances to precisely identify and attack cancer cells. Anti-angiogenesis therapy uses substances that interfere with tumor blood supply. Patients for whom no established treatment is available may be eligible to enter a clinical trial of a new approach.19 Information about clinical trials can be obtained from one’s physician or the NCI Cancer Information Service Web site.20 Trials are conducted by cancer specialists throughout the United States. Scientific treatment facilities maintain a tumor reg- istry in which the details of cases treated at the facility are recorded, with follow-up queries sent annually to patients and/or their doctors. Data of this type are im- portant in assessing the results of treatment. dieT and CanCer prevenTion The fact that people with similar hereditary background living in different parts of the world can have different cancer patterns suggests that environmental causes play an important role, but the data are complex and difficult to interpret. Dietary factors may play a role in the development of certain cancers, but the proportion related to diet is not known. This section considers whether diet and dietary supplements can help prevent cancer. Whether any such approaches can treat cancer is discussed later in this chapter. The idea that dietary strategies might help prevent certain cancers first came to public attention in 1982 when the National Academy of Sciences (NAS)21 issued “interim guidelines” that included increased intake of foods rich in antioxidant nutrients and fiber. The ACS issued similar guidelines but has modified them in light of subsequent research. Its current version22 advises:

• Eat a variety of healthful foods, with an emphasis on plant sources. Include 5 or more servings of a variety of veg- etables and fruits each day.
• Choose whole grains in preference to processed (refined) grains and sugars.
• Limit consumption of red meats, especially those high in fat and processed meat products.
• Choose foods that help maintain a healthful weight. Bal- ance caloric intake with physical activity. Lose weight if currently overweight or obese.
• Adopt an active lifestyle. Adults should engage in at least moderate activity for 30 minutes or more on 5 or more days of the week. Children and adolescents should engage in at least 60 minutes per day of moderate-to-vigorous physical activity at least 5 days per week.
• If you drink alcoholic beverages, limit consumption.

No scientific data indicate what proportion of cancers may be prevented by following such advice. However, it is unlikely to cause harm and may provide additional benefit such as lowering the incidence of cardiovascular disease and Type II diabetes. In 2007, the Cochrane Collaboration Colorectal Cancer Group23 concluded that calcium supplements may help prevent precancerous intestinal polyps, but no clinical trial has directly demonstrated an effect on the development of colorectal cancer. Questionable Anticancer Supplements The health-food industry is usually quick to exploit new scientific information to its advantage. The 1982 NAS report on diet, nutrition, and cancer specified that since it was not known which dietary factors, if any, might be helpful, supplementation with individual nutrients was not advisable. A few months after the report was issued, however, several products containing dehydrated veg- etables and various nutrients were marketed as though the report had supported their use for cancer prevention. Government actions stopped some of these promotions, but others have taken their place. In recent years, un- substantiated cancer-prevention claims have been used to market “antioxidant” supplements (see Chapter 11). Fiber-containing pills have been marketed with sug- gestions that they can help prevent certain cancers. How- ever, this idea has no scientific support. Kritchevsky24 has noted that dietary fibers have value beyond their possible role in preventing colon cancer. He emphasized that “a high-fiber diet is not merely a low-fiber diet with fiber added. . . . All components of diets containing fiber- rich foods are important.” Part Four Personal Health Concerns334 figure 16-1. Message from a comic book designed to promote Laetrile and undermine public trust in conventional methods of cancer treatment. Condemning accepted methods is a standard practice in medical quackery. Actually, no link has been established between di- etary fiber intake and colon cancer. In 1999 researchers reported that their 16-year prospective study of 88,757 women found no significant relationship between fi- ber intake and the occurrence of precancerous polyps (colorectal adenomas).25 In 2001, the Cochrane Collabo- ration Colorectal Cancer Group26 reviewed five clinical trials and concluded that increasing fiber in a Western diet for two to four years did not lower the risk of bowel cancer. Green Tea Green tea has been widely promoted as effective in preventing stomach cancer. However, in 2001, the New England Journal of Medicine27 published a large study that found no supporting evidence. The study involved more than 26,000 Japanese men and women who were followed-up over a 9-year period. No relationship was found between the number of cups consumed and the incidence of stomach cancer. An accompanying editorial explained why previous data suggesting that green tea might have a protective effect might be wrong.28 susCepTibiliTY To CanCer QuaCKerY Cancer is a major field of exploitation of unproven and fraudulent treatments. People use questionable methods mainly because of fears that cancers are incurable and costly to treat, that treatment might be uncomfortable and mutilating, and that they will be socially stigma- tized. If their doctors seem discouraged or say that they can offer only palliative care, patients often lose hope and feel abandoned. Proponents of “sure cures” cater to these feelings by appearing optimistic and caring while they promote false hopes. Figure 16-1 is an example of literature designed to undermine public trust in proven cancer treatment. Figure 16-2 shows an old ad for a product “guaranteed” to cure any cancer. People’s capacity to be fooled should not be underes- timated. During the 1940s, William Koch, M.D., Ph.D., acquired a large following of believers in a remedy that he claimed was 1.32 parts glyoxylide per trillion parts water. More than 3000 assorted practitioners paid $25 per ampule and charged patients up to $300 per injection. A product analysis found only distilled water. Several factors can influence people to believe they have been helped by an unconventional method. Some patients who believe they have been cured of cancer never had it in the first place. Patients who use a question- able treatment along with proven treatment may credit the questionable method for any improvement. Even fatal forms of cancer can have some ups and downs in their course, so that the patient may feel better on some days than others. A period of well-being following use of an unorthodox method can be misinterpreted as “improvement” or even “cure.” (See the “Heads I Win, Tails You Lose” box.) Some patients with slow-growing cancers are misrepresented as cured. Doctors sometimes give too pessimistic a prognosis. A patient who tries a nonstandard treatment and lives longer than predicted by a doctor may credit the alleged remedy instead of realizing that the doctor’s prediction was too pessimistic. Dr. William Jarvis has noted: Any facility that treats large numbers of cancer patients will encounter some whose survival is much longer than average but still within expected variations. But only the quacks use these people to lure other cancer patients to their facility. Chapter Sixteen Cancer 335 Dr. Malcolm Brigden,29 a Canadian cancer specialist, noted that nonstandard treatments are appealing because their methods are explained in common-sense terms that seem plausible and offer an opportunity to play an active role in fighting the disease: (a) cancer is a symptom, not a disease; (b) symptoms are caused by diet, stress, or environment; (c) proper fitness, nutrition, and mental at- titude allow biologic and mental defense against cancer; and (d) conventional therapy treats the symptoms rather than the disease and weakens the body’s reserves. Many “alternative” promoters encourage patients to blame themselves for becoming ill. Cassileth and colleagues30 at the University of Pennsylvania Cancer Center interviewed 304 cancer center inpatients and 356 patients under the care of unconventional practitioners elsewhere. Among those who used “alternative treat- ment,” many believed that their cancer could have been prevented through diet (32% of patients), stress reduction (33%), or environmental changes (26%) and therefore was reversible by the same means. QuesTionable MeThods Cancer quackery is as old as recorded history and almost certainly has existed since cancer was recognized as a disease. Thousands of worthless folk remedies, diets, drugs, devices, and procedures have been promoted for cancer management. The ACS has defined questionable methods as “diagnostic tests or therapeutic modalities which are promoted for general use in cancer prevention, diagnosis, or treatment and which are, on the basis of careful review by scientists and/or clinicians, not deemed proven nor recommended for current use.”31 The ACS has published detailed critical reports on many questionable methods that have achieved notoriety. In recent years, however, it has softened its approach and issued mostly brief reports on “complementary and alternative methods.” The mere fact that something is unproven does not make it “questionable.” For science to advance, research- ers and clinicians must be free to try new approaches. Before any cancer treatment is accepted for general use by physicians, it must undergo rigorous scientific scrutiny. When evaluating an unproven method, experts

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