Exercise and Breast Cancer Risk
A number of studies have found a link between exercise and a lower risk for breast cancer. What’s less clear is whether starting exercise later in life lowers the risk. Here’s the good news. If you were a couch potato during the first part of your life and only discovered the benefits of exercise when you were well into middle-age, new research will put your mind at ease.
French researchers recently analyzed a group of 37 well-conducted studies related to breast cancer and exercise. These studies looked at more than four million women that took part in studies over a 26 year period. It included all published studies carried out on exercise and breast cancer incidence. The results were encouraging.
Women at the highest levels of physical activity had a 12% lower risk overall for developing breast cancer compared to the least active women. Just as importantly, this study showed you don’t have to begin exercising early in life to get the protective benefits. Even if you start later in life, you can still enjoy the protective benefits of exercise
Exercise and Breast Cancer Prevention: How Might Exercise Lower the Risk?
A number of theories as to how exercise lowers breast cancer risk have been proposed. For one, exercise helps with weight control. Women who are overweight and obese typically have higher estrogen levels. That’s not good since estrogen fuels the growth of some breast tumors. But, a recent Swedish study suggests there may be another explanation. It showed that thin but unfit women who are physically inactive are at greater risk for breast cancer despite their lower body weight.
Physically activity seems to trump body weight when it comes to breast cancer prevention. On the other hand, obesity is still a risk factor for breast cancer. In fact, in this study, obese, inactive women were at the highest risk of all. One cautionary note. Hormone replacement therapy after menopause offsets the protective benefits of exercise on breast cancer risk.
Are there ways exercise reduces breast cancer risk? Some research shows exercise alters the way estrogen is metabolized by the liver. Estrogen is broken down into two forms called 2-alpha hydroxyestrone and 16-alpha hydroxyestrone. Women who have higher levels of 2-alpha hydroxyestrone relative to 16 alpha-hydroxyestrone appear to have a lower risk for breast cancer compared to women with a lower ratio of these estrogen breakdown products. Interestingly, exercise seems to increase 2-alpha hydroxyestrone levels relative to the 16 forms. So exercise may cause estrogen to be broken down to a less carcinogenic form.
Another theory is exercise reduces inflammation. Inflammation seems to fuel the growth of some breast cancers. In addition, exercise has beneficial effects on immunity and the immune system is important for keeping breast cancer cells in check.
How Much Exercise Do You Need to Get the Benefits?
In this study, researchers found the greatest protective benefits in women that exercised about an hour a day. That doesn’t mean lesser amounts of exercise are of no value. The risk was also reduced in women that exercised less than an hour but not as much.
Are some forms of exercise more protective than others? Based on this study, you can lower your risk by doing any form of exercise. Some studies have shown vigorous exercise lowers the risk more, but the key is to stay consistently active.
Other Ways to Lower Your Risk for Breast Cancer
Obviously, exercise is something you want to do if you want to reduce your risk for breast cancer. Other ways to lower breast cancer risk:
Eat more fruits and vegetables. They’re a natural source of fiber and antioxidants that may lower your risk for breast cancer based on some studies.
Limit the amount of alcohol you drink to one glass of wine or less a day. Higher alcohol consumption has been linked with a greater risk for breast cancer according to some research. Getting adequate amounts of folate in your diet may help to offset this risk.
Avoid weight gain after menopause. Weight gain after menopause has been linked with an increased breast cancer incidence. Exercise helps here too!
Talk to your doctor about your risk factors and the pros and cons of hormone replacement therapy. Combination hormone replacement therapy has been linked with an increased risk for breast cancer, although estrogen therapy alone has not. If you still have a uterus, you can’t take estrogen without progesterone because estrogen taken alone stimulates the growth of the lining of your uterus.
Other less proven ways to lower your risk include avoiding exposure to pesticides and BPA in plastic products, limiting exposure to radiation (x-rays, CTs, etc.)
The Bottom Line?
Exercise is a natural way to lower your risk for breast cancer. Even if you started late in life, you can still enjoy the protective effects of regular physical activity – so get moving!
References:
Centers for Disease Control and Prevention. “Cancer Prevention and Control”
Science Daily. “Regular physical activity reduces breast cancer risk irrespective of age”
The Telegraph. “Being slim will not ward off breast cancer, women need to exercise as well”
Epidemiology. 2000 Nov;11(6):635-40.
Medscape Family Medicine. “Prospective Study of Physical Activity and Risk of Postmenopausal Breast Cancer”
WebMD. “Steps Women Can Take to Reduce Risk of Breast Cancer”
Harvard Health Publications. “Study supports alcohol, breast cancer link”
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