October 3, 2002 Thursday Ontario Edition

SECTION: Pg. L01

LENGTH: 1410 words

HEADLINE: The picture of health

BYLINE: Donna Jean MacKinnon, Toronto Star

HIGHLIGHT:
Cancer risk can be significantly reduced by making lifestyle changes

BODY:
An ounce of prevention is worth a pound of cure.

This ancient adage now applies to breast cancer, health professionals say.

Research indicates that if women take control of various factors in their daily lives, they can reduce their risk of breast cancer by up to 50 per cent.

This is called primary prevention and in medical circles, the emphasis is beginning to shift from catching the disease early (secondary prevention) to stopping it before it starts.

That means paying attention to environmental and lifestyle factors like physical activity, diet, smoking, alcohol, obesity and surroundings. "The time is right for identifying ways of preventing breast cancer. We all want some method of taking control of this disease," says Marilyn Schneider, executive director of the Canadian Breast Cancer Research Initiative (CBCRI), which is funding several projects to find out more about primary prevention.

This year an estimated 20,700 Canadian women will develop breast cancer and 5,400 will die from it. While it is rare, breast cancer does occur in men. An estimated 140 will be diagnosed this year and 40 will die from it.

Only 5 to 10 per cent of all cases can be traced to genetics; the rest are due to unknown causes. That's where prevention comes in.

According to researcher Dr. Christine Friedenreich, physical activity goes a long way to reducing the risk. In fact, there is convincing evidence that women who have been active throughout their lives decrease their risk of breast cancer by 42 per cent.

This conclusion is based on several studies monitoring the effects of various physical activities on women's health and a recent study conducted by Friedenreich involving 2,500 Albertans, half with breast cancer.

"We analyzed their total lifetime activity and the activity level involved in their occupations," says Friedenreich, an epidemiologist at the Alberta Cancer Board.

But it's never too late to get moving, says Friedenreich, whose research shows that post-menopausal women who have been lifelong couch potatoes can catch up.

She advocates six hours of activity per day but that doesn't necessarily mean sweating it out in the gym > walking to the fax machine, snow shovelling, housework and gardening all count.

No one yet understands why exercise helps reduce the risk of breast cancer, according to Friedenreich, who's just been awarded $1.13 million by the CBCRI to try to answer that question in a study of 334 post-menopausal women.

Civil servant Susan McCann doesn't have to be convinced about the need to exercise. It's been part of her routine at least four times weekly for the past 15 years > partly for health reasons and partly for vanity. In her late 30s, she is youthful, healthy and energetic.

"I've read a lot about the health benefits of exercise, especially in the prevention of heart disease," she says. "Now it seems exercise is considered beneficial for lots of diseases. I believe you can't afford not to work out."

Physical activity accounts for part of the prevention picture but there are other lifestyle variables that play a role. Researcher Dr. Robert Casper believes exposure to light at night contributes to the risk of breast cancer, and therefore advises sleeping in a very dark room.

Research has shown a correlation between the amount of artificial light people are exposed to at night and incidence of breast cancer, says Casper, a professor in the obstetrics and gynaecology department at the University of Toronto and a senior scientist at Mount Sinai Hospital.

"The speculation is this finding is related to melatonin production," says Casper, who will be the keynote speaker at the 12th annual Genesis Awareness Breakfast, on Oct. 28 at the Fairmount Royal York Hotel.

"People > like shift workers > exposed to night light don't get enough melatonin." That may increase cancer risk.

Electromagnetic fields (EMF) are another enemy, particularly for people who already have breast cancer, according to Magda Havas, associate professor in environmental and resource studies at Trent University.

"The literature shows that women under 50 with estrogen-responsive breast cancer are most at risk," Havas says.

She describes the typical home as a minefield of electromagnetic fields: vacuum cleaners, stoves, older electric blankets, flourescent lights, electric alarm clocks and so on. But the biggest threat is your computer, she says. It emits a magnetic field above 20 milli Gauss (mG) on a scale that places 12 mG as a safe level.

Havas advises magnifying the type and moving farther from the screen. Each foot away from the screen lessens the harm > at two feet away, there is one-tenth the harm.

People who live in houses with pre-1940s electric wiring are exposed to high EMF levels as are those who have outdoor power lines that are parallel with second-floor bedrooms.

These findings are based on two important research papers, according to Havas. One epidemiological study didn't turn up any evidence that an electromagnetic field will initiate breast cancer, but it did show that EMF exposure makes the cancer more aggressive in people who already have it. In another study, breast cancer cells were seen to multiply when exposed to different magnetic fields. Still other experiments have shown that the cancer drug tamoxifen is less effective if a patient has a high magnetic field in her environment.

"If you are receiving chemotherapy, the drug is not going to be as effective and you'll have a poorer chance of recovery," Havas says.

Havas's message is simple: Minimize exposure to electric equipment and wiring.

Diet may be another culprit, according to the experts. Dr. Norman Boyd, head of the division of epidemiology and statistics at the Ontario Cancer Institute, indicates there is strong evidence diet may play a role in breast cancer.

While there is no definitive study that proves a fatty diet is linked to breast cancer, Boyd comments there's no good reason for eating a lot of fat.

Nutritionist Rose Reisman, author of The Art of Living Well (Viking Canada, $29) a just published cookbook that will raise money for the Canadian Breast Cancer Foundation, is a strong advocate of eating for disease prevention.

It has been observed in places like Asia, where there is a low-fat and high-fibre diet, breast cancer rates are lower.

"It could be that women who eat less fat and more fibre have lower levels of estrogen. And we know higher levels of estrogen increase the risk of breast cancer," Reisman explains in her book.

She also states that weight gain, especially after menopause, is linked to a higher risk of breast cancer, due to an increased level of estrogen produced in fat cells.

Reisman's advice is to concentrate on (low-calorie) dark green vegetables (antioxidants), three servings of fish per week, containing beneficial omega-3 fatty acids, and to include in your diet yogurt, which impedes growth of breast cancer cells, and tea, another antioxidant.

According to Reisman soy, common in Asian countries, may be a factor in keeping breast cancer levels low. It contains "protective agents" that block a woman's own estrogen, resulting in breast cells having less contact with the estrogen that drives breast cancer, according to Reisman.

Both Reisman and Dr. Ellen Warner, a staff oncologist at Sunnybrook Regional Cancer Centre, warn, however, that women should avoid excessive amounts as there are no definitive studies proving its benefits and some new research indicates too much soy may be harmful.

She confirms there is a consistent link between alcohol and breast cancer, although "no one really knows why.

"But there is evidence it reacts with other factors like HRT, hormones and family history." Warner allows one alcoholic drink a day, six days out of seven, but no more.

Smoking is out as far as Warner is concerned.

"Don't," she says flatly. "Smoking increases blood clots and that can be fatal. Clearly, it is a bad thing for women with breast cancer."

But she adds that while there appears to be a link between smoking and every other cancer, a connection with breast cancer is not so clear. Warner explains the theory: Smoking creates harmful carcinogens, which cause cancer, but it appears to lower estrogen levels. Second-hand smoke also creates carcinogens in the body, but the difference is, it doesn't seem to suppress estrogen production.