預防乳腺癌：生活方式的因素，可以降低風險

Breast cancer prevention starts with your own health habits — such as staying physically active, limiting alcohol and eating right.

Can healthy eating and regular exercise really contribute to breast cancer prevention? So far, the evidence says yes. What's more, if you combine these risk-reducing habits with limiting your exposure to substances that promote the disease, you'll benefit even more.

When it comes to breast cancer prevention, the risks you can't control — such as your age and genetic makeup — may loom large. But there are some breast cancer prevention steps you can always take on your own. Although these measures provide no guarantee that you won't develop the disease, they'll give you a start toward breast cancer prevention.

Diet and exercise tips for breast cancer prevention

Among the easiest things to control are what you eat and drink and how active you are. Here are some strategies that may help you decrease your risk of breast cancer:

• Limit alcohol. A link exists between alcohol consumption and breast cancer. How strong a link remains to be determined. The type of alcohol consumed — wine, beer or mixed drinks — seems to make no difference. To protect yourself from breast cancer, consider limiting alcohol to less than one drink a day or avoid alcohol completely.
• Maintain a healthy weight. There's a clear link between obesity — weighing more than is appropriate for your age and height — and breast cancer. This is especially true if you gain the weight later in life, particularly after menopause. Experts speculate that estrogen production in fatty tissue may be the link between obesity and breast cancer risk.
• Stay physically active. Regular exercise can help you maintain a healthy weight and, as a consequence, may aid in breast cancer prevention. Aim for at least 30 minutes of exercise on most days of the week. If you haven't been particularly active in the past, start your exercise program slowly and gradually work up to a greater intensity. Try to include weight-bearing exercises such as walking, jogging or aerobics. These have the added benefit of keeping your bones strong.
• Consider limiting fat in your diet. Results from the most definitive study of dietary fat and breast cancer risk to date suggest a slight decrease in risk of invasive breast cancer for women who eat a low-fat diet. But the effect is modest at best. However, by reducing the amount of fat in your diet, you may decrease your risk of other diseases, such as diabetes, cardiovascular disease and stroke. And a low-fat diet may protect against breast cancer in another way if it helps you maintain a healthy weight — another factor in breast cancer risk. For a protective benefit, limit fat intake to less than 35 percent of your daily calories and restrict foods high in saturated fat.

Hormone therapy: Long-term use may undermine breast cancer prevention

Talk with your doctor about discontinuing long-term hormone therapy. Study results from the Women's Health Initiative (WHI) raised concerns about the use of hormone therapy for symptoms of menopause. Among other problems, long-term treatment with estrogen-progestin combinations, such as those found in the drug Prempro, increased the risk of breast cancer in women who participated in the trial.

If you're taking hormone therapy for menopausal symptoms, ask your doctor about your options. You may be able to manage your menopausal symptoms with exercise, dietary changes or nonhormonal therapies that have been shown to provide some relief. If none of these is effective, you may decide that the benefits of short-term hormone therapy outweigh the risks. In that case, consider using the lowest dose of hormone therapy that's effective for your symptom relief and plan on using it only temporarily, not long term.

Birth control pills and breast cancer prevention: No easy answers

There's no evidence of an across-the-board link between birth control pill use and breast cancer risk. Analysis of combined data from many older studies suggests a slight increase in risk of premenopausal breast cancer. The pills used in these studies, however, include preparations that contained higher estrogen doses than what is available in preparations prescribed today. The analysis of these older oral contraceptives also showed that women who took the pill for four or more years before their first full-term pregnancy had a larger increase in premenopausal breast cancer risk. Still, experts analyzing all the risk data estimate that birth control pill use causes, at most, 4.7 out of 10,000 cases of premenopausal breast cancer.

Pesticides and antibiotics: Use with caution

Breast cancer incidence may be linked to both pesticide exposure and overuse of antibiotics. But research isn't conclusive. Until further studies are conducted and more is known about these possible links, be aware of how these substances might counterbalance your efforts at breast cancer prevention.

• Exposure to pesticides. The molecular structure of some pesticides closely resembles that of estrogen. This means they may attach to estrogen receptor sites in your body. Although studies haven't found a definite link between most pesticides and breast cancer, researchers have learned that women with elevated levels of pesticides in their breast tissue have a greater breast cancer risk.
• Unnecessary antibiotics. Scientists recently found a link between antibiotic use and breast cancer — the longer antibiotics were used, the greater the risk of breast cancer. Researchers caution, however, that other factors, such as underlying illness or a weakened immune system, rather than antibiotics themselves, may account for the elevated cancer risk.

Do what you can

In addition to lifestyle changes, be vigilant about early detection of breast cancer. Start having yearly mammograms at age 40. If you notice any breast changes, such as a new lump or skin changes, make an appointment to see your doctor for evaluation.

Nothing you do can guarantee your life will be cancer-free. But if you practice healthy habits and consult your doctor about extra measures you can take, you may at least reduce your risk of this potentially fatal disease.

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By Mayo Clinic Staff

Dec. 12, 2008

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