Prevention and Lifestyle Factors:

Exercise

Regular exercise, particularly vigorous exercise, may offer some modest protection against breast cancer. Exercise can help reduce body fat, which in turn lowers levels of cancer-promoting hormones such as estrogen. The American Cancer Society recommends engaging in 45 - 60 minutes of physical activity at least 5 days a week.

Exercise can also help women who have been diagnosed with breast cancer and may help reduce the risk of breast cancer recurrence. Studies indicate that both aerobic and weight training exercises benefit the body and the mind, and improve quality of life for breast cancer survivors.

Physical activity contributes to health by reducing the heart rate, decreasing the risk for cardiovascular disease, and reducing the amount of bone loss that is associated with age and osteoporosis. Physical activity also helps the body use calories more efficiently, thereby helping in weight loss and maintenance. It can increase basal metabolic rate, reduces appetite, and helps in the reduction of body fat.

Dietary Factors

Despite much research on the association between diet and breast cancer, there is still little consensus. The best advice is to eat a well-balanced diet and avoid focusing on one "cancer-fighting" food. The American Cancer Societyâ ' s dietary guidelines for cancer prevention recommend that people:

• Choose foods and amounts that promote a healthy weight.
• Eat 5 or more servings of fruits and vegetables each day.
• Choose whole grains instead of refined grain products.
• Limit consumption of processed and red meat.
• Women should limit alcohol consumption to 1 drink per day (women at high risk for breast cancer should consider not drinking alcohol at all).

For breast cancer survivors, the American Cancer Society recommends diets that include lots of fruits and vegetables, low amounts of saturated fat (from meat and high-fat dairy products), moderation in soy foods, and moderate or no alcohol consumption.

Here are results from recent studies evaluating diet and breast cancer, for preventing both the development of cancer and its recurrence:

Fats. Research is still mixed on the role that fats, and which specific types of fats, play in breast cancer risk and prevention. Several studies have indicated that red meat, which is high in saturated fat, may increase breast cancer risk when eaten in large quantities on a daily basis. (Red meat is also high in iron, which in itself may increase breast cancer risk.) According to results from the Womenâ ' s Health Initiative study of dietary fat and breast cancer, there is no definite evidence that a low-fat diet will help prevent breast cancer. However, the study suggested that women who normally eat a very high-fat diet may benefit by reducing their fat intake. In the study, the low-fat diet reduced blood estrogen levels by 15%. The low-fat diet also appeared to reduce the risk for developing progesterone receptor-negative tumors.

Fruits and Vegetables. Fruits and vegetables are important sources of antioxidants, which may help protect against the tissue damage linked to increased cancer risk. Antioxidants include vitamin C, vitamin E, and carotenoids such as beta-carotene and lycopene. Richly colored fruits and vegetables -- not supplements -- are the best sources for these nutrients. These fiber-rich foods are an essential part of a healthy diet. However, it is not clear whether fruits and vegetables can specifically prevent breast cancer development or recurrence.

Calcium and Vitamin D. Eating lots of foods rich in calcium and vitamin D (such as yogurt and milk) may modestly reduce the risk of breast cancer for premenopausal women. Low-fat or non-fat dairy products are a healthier choice than high-fat ones.

Soy. Soy is an excellent low-fat protein alternative to meat. Soy contains phytoestrogens, which are estrogen-like plant chemicals. In particular, soy contains a type of phytoestrogen called isoflavones. Because many soy foods (such as tofu) are eaten in Asian countries where women tend to have a lower incidence of breast cancer, research has focused on whether soy may have a protective effect. To date, the evidence does not indicate that soy foods or supplements can reduce breast cancer risk. In addition, some studies suggest that high intakes of soy may actually increase the risk of estrogen-responsive cancers such as breast cancer. Some animal studies have suggested that the isoflavone compound genistein may reduce the protective properties of tamoxifen, a drug used to prevent breast cancer in high-risk women. The American Cancer Society recommends that women with breast cancer eat only moderate amounts of soy foods and avoid taking dietary supplements that contain high amounts of isoflavones.

Specific Preventive Measures for High-Risk Women

Lifestyle Factors. Premenopausal women at higher risk, usually because of family history, should take as many preventive measures as possible, starting at an early age. The following lifestyle choices may be beneficial:

• Exercising and eating healthily is the first essential rule.
• High-risk premenopausal women may choose alternatives to oral contraceptives and, if feasible, consider having children early in their life.
• High-risk postmenopausal women may want to forego hormone replacement therapy.
• Any woman at high risk for breast cancer should consider avoiding alcohol or drink it very sparingly.

Tamoxifen and Raloxifene. Drugs known as selective estrogen-receptor modulators (SERMs) act like estrogen in some tissues but behave like estrogen blockers (anti-estrogens) in others. Two SERMs -- tamoxifen (Nolvadex) and raloxifene (Evista) -- are approved for breast cancer prevention for high-risk women. Tamoxifen and raloxifene are not recommended as prevention for women at low risk for breast cancer or its recurrence. Women at high risk for breast cancer should discuss with their doctors the risks and benefits of SERMs.

Tamoxifen (Nolvadex) is the most studied of these drugs. It is currently used to treat breast cancer and was the first drug approved for prevention. Evidence strongly suggests that it halves the risk for estrogen receptor-positive cancers in high-risk women, including those with BRCA2 mutations (although possibly not BRCA1). It also helps prevent recurrence in women who have been treated for breast cancers. However, it has no protective effects against estrogen receptor-negative (hormone-insensitive) cancers.

Tamoxifen can increase the risk for uterine (endometrial) cancers. It can also increase the risk for blood clots, strokes, and endometriosis. Less serious side effects include hot flashes and vaginal discharge.

Raloxifene (Evista) was approved in 2007 for prevention of breast cancer in postmenopausal women with osteoporosis and postmenopausal women at high risk for invasive breast cancer. Raloxifene was previously approved for prevention and treatment of osteoporosis in postmenopausal women. Studies indicate that it works as well as tamoxifen in reducing the risk of invasive breast cancer

One of raloxifeneâ ' s main benefits is that it has a lower risk than tamoxifen of causing uterine cancer and blood clots. However, women with a history of blood clots in the legs, lungs, or eyes should not take raloxifene. Although studies indicate raloxifene does not increase the risk of stroke, it can increase the risk of dying from a stroke. Women with a history of or current risk factors for stroke or heart disease should discuss with their doctors whether raloxifene is an appropriate choice.

Less serious side effects of raloxifene include hot flashes, leg cramps, swelling of the legs and feet, flu-like symptoms, joint pain, and sweating. Raloxifene can cause birth defects and is approved only for postmenopausal women. It should not be taken with the cholesterol-lowering drug cholestyramine (Questran) or with estrogens.

Investigational Drugs for Breast Cancer Prevention.Aromatase inhibitors such as anastrazole (Armidex), letrozole (Femara), and exemestane (Aromasin) are effective treatments for postmenopausal women with hormone-receptor positive breast cancer. Like tamoxifen, these drugs are also being investigated for protection in high-risk women. However, aromatase inhibitors may decrease bone mineral density and cognitive function, and increase the risk for falls.