12 ways to prevent breast cancer

Here are some of the choices YOU can make to boost your good health and help lower your risk of breast cancer.

1. Stay active
Of all of the lifestyle choices women can make to reduce breast cancer risk, physical activity tops the list. According to an analysis of more than 50 studies carried out by Christine Friedenreich, an epidemiologist at the Alberta Cancer Board in Calgary, 45 to 60 minutes of moderate activity at least five days a week reduces breast cancer risk by a dramatic 30 to 40 per cent. Anything that gets your heart rate up and leaves you a bit sweaty and out of breath -- for example, a brisk walk -- qualifies as moderate physical activity. "Exercise can be anything from carrying loads of laundry to being active with your kids," says Brigitte.

On the other side of the coin, being sedentary boosts your risk of breast cancer. According to the Society of Obstetricians and Gynaecologists of Canada (SOGC), lack of exercise increases breast cancer risk by 60 per cent.

Don't fret too much if you've never exercised. Women who only become active after menopause have a rate of breast cancer that's close to that of lifelong exercisers. "It's best if people are active throughout their lives but if they haven't been, they can still benefit from exercise," says Friedenreich. "It's never too late to start to be physically active."

Why does exercise cut cancer risk? Researchers suspect that physical activity helps keep women lean. And staying lean prevents fat cells from producing extra estrogen, the hormone responsible for most breast cancers. "It all adds up to lowering your estrogen levels; you want to do everything in your power to keep your circulating estrogen levels low," says Brigitte.

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2. Maintain a healthy weight
Keeping a healthy body weight -- defined as a body mass index (BMI) of less than 25 kg/m2 -- protects women against breast cancer. But just how little weight you can gain and still be protected is not yet known. According to Health Canada, even a small weight gain -- as little as five kilograms (11 pounds) -- increases breast cancer risk, especially among postmenopausal women. But the Harvard Nurses' Health Study, a major ongoing research effort at the Harvard School of Public Health in the United States, found that the breast cancer risk doesn't kick in until there's a much greater weight gain. Every two years women enrolled in the Nurses' Health Study answer questions about their diet, lifestyle and health, and results from these assessments are published regularly. As part of this study, researchers found that women who had gained 20.5 kilograms (45 pounds) or more after the age of 18 and who had never used hormones had double the risk of postmenopausal breast cancer than women who had not gained weight. Women who did not use hormones and who did not gain weight in adulthood were at the lowest risk for postmenopausal breast cancer. The bottom line: Don't gain a lot of weight!

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3. Limit alcohol intake
Consuming alcoholic beverages increases estrogen in the blood and therefore ups your breast cancer risk. There's plenty of evidence of this: an analysis of more than 50 studies by the Collaborative Group on Hormonal Factors in Breast Cancer found that every alcoholic drink increases breast cancer risk by about seven per cent. Researchers from the Nurses' Health Study reported that postmenopausal women who drank an average of 1.5 drinks a day were 30 per cent more likely than nondrinkers to develop breast cancer. And the SOGC warns that consuming more than two alcoholic drinks a day increases breast cancer risk by 60 per cent.

However, this increased risk can be tempered by consumption of folate. One study from the Mayo Clinic in Rochester, Minn., found that the breast cancer risk of older women who drank alcohol but who also ate folate-rich foods, such as citrus fruits, tomatoes and vegetables, or took folate supplements, was about the same as that of nondrinking women who didn't consume much folate.

The Canadian Breast Cancer Foundation recommends that all women play it safe and limit their alcohol consumption to no more than one drink (five ounces of wine, 12 ounces of beer or 1.5 ounces of liquor) per day.

4. Eat more vegetables and fruit
There's growing evidence that eating vegetables and fruit lowers your risk of cancer in general, and, to a lesser extent, breast cancer in particular, says Fran Berkoff, a registered dietitian in Toronto.

At play here are plant chemicals, or phytochemicals. Some phytochemicals take up space on cells where the body's own estrogen would otherwise attach, thereby reducing exposure to the body's hormones. The Cancer Project, a program of the Physicians Committee for Responsible Medicine in Washington, D.C., says such potent phytochemicals are found in cruciferous vegetables, including broccoli, cauliflower and brussels sprouts, as well as in fresh garlic and, in smaller amounts, in onions, chives and leeks. Other phytochemicals are thought to behave like antioxidants, protecting the body from molecules that damage DNA in cells and set the stage for cancerous changes. Berkoff says these phytochemicals are found in black and green teas, and some fruits and vegetables, such as apples, blueberries, citrus fruits and peppers.

Since you may need several of these different phytochemicals to lower your cancer risk, it's probably wise to eat a variety of fruit and vegetables every day, says Berkoff, adding, "We can't tell women how much they reduce their risk by eating the recommended daily intake but it can't hurt to eat healthy foods, and if it offsets your breast cancer risk even a little, you're just that much further ahead."

The Canadian Cancer Society recommends five to 10 servings of vegetables and fruit a day to help lower your cancer risk.

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5. Eat the right fats
Observational studies show that Asian women, who traditionally consume a diet relatively low in fat, have much lower rates of breast cancer than do Canadian women. Other research shows that the higher the dietary fat intake across a population of women, the higher their breast cancer rates. Still other studies that compared diets of women in the same country suggested that dietary fat increases breast cancer risk.

While not all studies have come to the same conclusion, there's now enough evidence supporting a possible association between dietary fat and breast cancer to justify a larger, controlled study to determine, once and for all, if the fat you eat affects your breast health, says Cary Greenberg from Princess Margaret Hospital in Toronto. Greenberg is a coordinator for just such a study: the Diet and Breast Cancer Prevention Study will compare two groups of similar-risk women -- one on a reduced-fat diet and the other maintaining their normal diet. (For details, visit www.uhnres.utoronto.ca/bccancer.)

But while some fats may increase breast cancer risks, other fats may be protective. Studies have concluded that omega-3 fatty acids, found in some fish, can prevent the development and spread of breast cancer in animals. In women, the role of omega-3 fatty acids in preventing breast cancer is an interesting area, but the research is still preliminary, says Berkoff.

There is good evidence that omega-3 fatty acids protect the heart, though. If eating fish, especially fatty fish, at least twice a week, as recommended by the American Heart Association, is good for the heart, it's probably good for overall health -- including breast health.

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6. Carefully consider HRT
The combination of estrogen and progestin, another female hormone, in hormone replacement therapy (HRT) increases breast cancer risk, according to two large studies -- the Women's Health Initiative (WHI) study in the U.S. and the Million Women Study in the United Kingdom. The WHI study uncovered eight more cases of breast cancer per 10,000 women taking combined HRT (estrogen plus progestin) an average of 5.2 years than among non-HRT users. (WHI women taking estrogen alone had no increased breast cancer risk.) According to the SOGC, HRT increases breast cancer risk by 2.3 per cent per year of HRT use.

Perhaps the good news is that the breast cancer risk among HRT users does not increase until four to five years after starting the therapy. As well, "the risk goes down as soon as you stop taking HRT," says Dr. Jennifer Blake, chief of obstetrics and gynecology at Sunnybrook and Women's College Health Sciences Centre in Toronto.

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