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Preventing Cancer

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Mammograms: To screen or not to screen?

The mammography debate rages on, newly fueled by results from a Canadian trial published in the Sept. 3, 2002, Annals of Internal Medicine.

The Canadian National Breast Screening Study (CNBSS) is the first trial designed specifically to assess screening mammography in women ages 40–49. In the early 1980s, the CNBSS recruited 50,430 women in this age group with no history of breast cancer. Half were assigned to receive annual mammograms; the other half, to receive “usual care,” meaning that mammograms were done only if a patient’s doctor recommended them.

After an average of 13 years, there were 105 breast cancer deaths in the mammography group and 108 in the usual care group — not statistically significant difference. The researchers concluded that mammograms are not justified for breast cancer screening in women under age 50.

Critics of the CNBSS trial said the data came from older technology, before improved imaging was available. The women who took part enrolled 20 years ago, when mammography images were less clear and radiologists weren’t as proficient at reading them.

But the American Cancer Society, the Centers for Disease Control and Prevention, and the National Cancer Institute advise women to get annual mammograms starting at age 40.

To further muddy the waters, the same issue of Annals of Internal Medicine that carried the CNBSS results published new guidelines for breast cancer screening from the U.S. Preventive Services Task Force (USPSTF). The USPSTF is a panel of health experts that analyzes published research and makes suggestions about preventive health care.

The group recommends having a mammogram every one to two years, starting at age 40. The authors assert that there is no convincing evidence to support the theory that starting annual screening at age 40 exposes women to undue harm, with minimal chances of finding cancer.

On the other hand, if mammograms can find breast cancer, why not start at age 40? For one, the screening test may adversely affect some women. False-positive results (which flag a problem when none exists) can lead to anxiety and further testing.

In defense of its recommendations, however, the USPSTF says that anxiety usually disintegrates after cancer is ruled out. And even when it doesn’t go away, anxiety doesn’t seem to discourage women from continuing their screening regimen.

If you have a family history of breast cancer or other risk factors, it makes sense to start mammograms at age 40 (perhaps earlier, depending upon your level of risk). For everyone else, a discussion with your doctor is the most sensible first step. If she or he feels annual mammograms are unnecessary for you, and you’re comfortable with the decision, waiting until you’re 50 should be fine.

November 2002 Update

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New Cancer Prevention Guidelines

While some risk factors for developing cancer, such as family history, can not be changed, there are ways for people to reduce their chances. The American Cancer Society (ACS) recently released new dietary and physical activity guidelines for cancer prevention.

One of the most basic tenets of a healthy diet is eating plenty of fruits and vegetables. The ACS recommends eating no less than 5 servings of a variety of fruits and vegetables every day. Many people have heard of antioxidants but aren't sure exactly what they are or what they do. Antioxidant nutrients (such as vitamin C, vitamin E, and carotenoids) protect the body against the tissue damage that occurs as a result of normal metabolism. Because such damage is associated with increased cancer risk, the antioxidant nutrients are thought to protect against cancer. Studies suggest that people who eat more vegetables and fruits, which are rich sources of these antioxidants, have a lower risk for some types of cancer, but studies of antioxidant supplements have not yet shown a reduction in cancer risk.

Choosing whole grains over processed (refined) grains and sugars will also help, so stick to whole grain rice, bread, pasta, and cereals. Also, limit your red meat intake. When you do eat it, choose the way you cook it carefully. While adequate cooking is necessary to kill harmful microorganisms in meat, some research suggests that frying, broiling, or grilling it at very high temperatures creates chemicals that might increase cancer risk. Braising, steaming, and poaching meats cuts down on the production of these chemicals.

Drinking too much alcohol is an established cause of cancers of the mouth, throat, liver, and breast. Therefore, the ACS recommends limiting alcoholic consumption to 2 drinks per day for men and 1 drink per day for women.

The ACS also reminds people to remember that "low fat" or "fat free" snacks like cakes and cookies are often high in calories. High sugar intake can lead to obesity and elevated insulin levels, conditions that increase cancer risk.

Physical activity is also an important component in the prevention of cancer. Adults should engage in moderate-to-vigorous activity (walking, leisurely bicycling, running, swimming) for 30 minutes or more at least 5 days a week.

Simple additions to your daily routine such as taking the stairs instead of the elevator, taking 10-minute exercise breaks at work, and walking to visit co-workers instead of emailing them are simple ways to increase your activity level.

An unhealthy diet and lack of exercise can lead to weight gain and obesity, conditions that are associated with developing cancers of the breast, colon, endometrium, esophagus, gallbladder, pancreas, and kidney.

In addition to the general guidelines set forth by the ACS, there are also answers to frequently asked questions about the rumored or theoretical relationships between cancer and such substances as aspartame, beta-carotene, calcium, coffee, fish oils, fluorides, folic acid, saccharin, and tea.

The ACS suggests that public, private, and community organizations create environments that support the adoption and maintenance of these healthful eating and physical activity behaviors. People should have access to healthful foods in schools, at work sites, and when on daily outings in their town or city.

For a copy of the complete set of guidelines, call the American Cancer Society at 1-800-ACS-2345.
April 2002 Update

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Surgery for GERD

In recent years, people suffering from severe, chronic heartburn that can’t be controlled with medications have turned to surgery with hopes for permanent relief and the prevention of esophageal cancer. But the results of a recent study that assessed the well being of patients a decade after they had surgery question its benefits.

Heartburn, also known as gastroesophageal reflux disease (GERD), occurs when the opening between the esophagus and stomach relaxes spontaneously, allowing acidic gastric juices to flow into the esophagus and cause irritation. Medications for GERD include antacids, proton pump inhibitors that decrease the amount of acid produced, and drugs that increase the tightness of the esophageal. Surgery, an option usually reserved for hard-to-treat GERD, involves folding the top of the stomach around the end of the esophagus to create a tighter opening. This procedure has become more popular with the development of minimally invasive techniques.

A study from the late 1980s of 247 heartburn patients found surgery was better than medication at controlling symptoms. However, ten years later a follow-up study of 239 of the original patients found many of the patients who underwent surgery still suffered from heartburn. Though their symptoms were less intense than those who received medication in the original study, 62% of the surgical patients still took antireflux medication regularly (compared to 92% of the medical patients).

The study also found that surgery failed to significantly decrease the risk for esophageal cancer compared to treatment with medication. Chronic heartburn is a risk factor for this cancer. However, the small size of the study combined with the low incidence of esophageal cancer did not rule out the possibility of a difference. A more surprising result of the study showed surgical patients were more likely to die than patients on medication. These deaths were not related to the surgery, but close to half (48%) were related to heart disease. The researchers were unprepared for this result and therefore have no data to explain this finding.

The results of this study suggest that while surgery may do a better job at controlling the symptoms of heartburn, it doesn’t eliminate the need for medication or decrease cancer risk. In general, surgery should be seen as an option of last resort for those patients whose symptoms are hard to treat with medication.
June 2001 Update

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Walking for Women: A Great Step Toward Fitness

Ask any doctor for his or her advice for healthy living and you'll find exercise a part of the prescription. However, it is one that patients must "fill" themselves and that can be tough. The most recent guidelines from the Centers for Disease Control and Prevention, the American College of Sports Medicine, and the Surgeon General's report recommend that individuals get at least 30 minutes of moderate-intensity activity on most (ideally all) days of the week. Yet 60% of Americans don't regularly engage in physical exercise at all.

Harvard Medical School researchers recently compared the effects of brisk walking with more vigorous forms of exercise, specifically in women. For this report, study investigators followed 72,488 women participating in the Nurses' Health Study for 11 years. At the start of the study in 1986, these women were all between the ages of 40 and 65 and had no known heart disease or cancer. They completed regular, detailed questionnaires about their physical activity.

Researchers found that vigorous exercise and brisk walking reduces the risk of heart attack for women by roughly the same amount. The bottom line is that brisk walking for three or more hours per week can reduce a woman's risk of cardiovascular disease by 30%-40%. Women who walk for a longer time or combine walking with other vigorous physical activity can expect to reduce their risk of heart disease even more. So women don't have to sign up for aerobics or train for a marathon to substantially reduce their heart disease risk. A good start is putting one foot in front of the other at a good pace. For more information on exercise and fitness, see page 51 of the Family Health Guide.

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Vitamin C: How Much Is Enough?

Vitamin C is touted as a potential weapon in combating a range of illnesses, from the common cold to cancer and heart disease.

No one believes that taking vitamin C supplements in moderate doses presents any danger, and foods rich in vitamin C (fruits and vegetables) offer real health benefits. But could consuming large amounts of vitamin C supplements be too much of a good thing?

Despite some theoretical dangers, vitamin C appears to have very few toxic effects. However, at very high doses, vitamin C can indeed cause problems. Diarrhea and abdominal bloating can result from taking several grams at once — a tactic that has been advocated by some for preventing and treating the common cold.

Studies show that high doses of vitamin C could lead to over-absorption of iron, which could potentially damage the heart, liver, and other organs. Too much vitamin C may also contribute to kidney stones or give false-positive readings on blood-stool tests. Such events occur rarely if ever, so these really are minor concerns. But, even if people are not endangering themselves much by taking large amounts of vitamin C, research suggests that they are not helping themselves either. Studies of dietary patterns show that people who get an average of 200 mg of vitamin C per day from fruits and vegetables have a lower risk of cancer — especially cancers of the mouth, esophagus, stomach, colon, and lung. Five servings of fruits and vegetables a day are enough to provide this much vitamin C. In research trials, consuming more vitamin C has not led to a detectable increase in health benefits. As for heart disease, there is evidence that marked vitamin C deficiency is associated with an increased risk of cardiovascular problems, but there is no proof that taking supplements offers additional benefits over those offered by a diet that includes the recommended amounts of fruits and vegetables.

Experts from the National Institutes of Health recently reviewed the evidence on this topic and concluded that, ideally, people should try to get their vitamin C from eating five servings of fruits and vegetables daily. Taking more than one gram (1,000 milligrams) of vitamin C per day should be discouraged because of the small, yet real, possibility of adverse effects. These recommendations do not mean that people who are taking vitamin C supplements or a multivitamin pill should stop, particularly if they just can't manage to eat enough fruits and vegetables. However, there is no reason to take high doses of vitamin C, and there may even be a small possibility of harm. For more information on vitamins and minerals, see page 43 of the Family Health Guide.

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