Here's how much you need to exercise to reduce your risk of breast cancer

14 October 2015

Dr Christine Friedenreich
Is 150 minutes of moderate physical activity each week enough to prevent cancer?

That’s what exercise guidelines have been telling us, but this amount is based on what science found is sufficient to reduce the risk of developing cardiovascular disease.

So Dr Christine Friedenreich of Alberta Health Services set out to determine the optimal amount of physical activity for cancer prevention.

The results of her Breast Cancer Exercise Trial in Alberta (BETA trial) are now in: being physically active for 300 minutes each week provides the greatest benefit for breast cancer risk reduction.

“A lot of people are rightfully concerned about cancer,” says Dr Friedenreich. “But exercise is a way to control your health and reduce your risk of developing cancer, and that’s a very empowering and positive message.”

Even though her study focused on breast cancer, the findings could also apply to other forms of cancer for which being overweight is a proven risk factor (e.g.; colorectal, esophageal, kidney).

How does exercise help to prevent cancer?

Being overweight or obese increases a person's risk of developing certain cancers, including breast.

Fat tissues are the main source of hormones that can increase the risk of developing breast cancer after menopause (breast cancer is most commonly diagnosed in women between the ages of 50 and 69) as well as affect the body’s immune and inflammatory responses, which also play a role in cancer development.

Increase your activity level

“There are benefits when you exercise for 150 minutes per week, so that’s already a good amount,” says Friedenreich. “But if you can do more – say 60 minutes, 5 days a week – there’s an even greater benefit.”

To reach the exercise target of 300 minutes per week, Dr Friedenreich recommends that you make physical activity part of your daily routine by:

  • using active transportation (e.g.; riding your bike, walking) to commute to work
  • walking to the grocery store
  • walking the dog more often
  • being active on the weekends (e.g.; ski, hike, swim)

“There is a need for some discipline to make exercise a priority,” says Friedenreich. “You should set aside time every day to do something active.”

The next step

The Canadian Cancer Society awarded Dr Friedenreich with an Interventions to Prevent Cancer Grant for a supplementary study of the BETA trial. This study will examine the long-term effects of this exercise program and will address two key questions:

  1. What are the long-term effects of the exercise program on body fat levels, hormone levels and inflammation?
  2. What factors explain whether or not women keep exercising 12 months after completing the trial?

“If the women stop exercising, do they still experience any benefits (i.e., less body fat)?” explains Dr Friedenreich.

And discovering the barriers to exercise could lead to the creation of strategies that’ll increase the likelihood that women will make physical activity a priority – improving their overall health.

Dr Friedenreich and her team will also examine participants’ sedentary behaviour to see if increased levels of exercise compensate for long periods of inactivity.

“Even though people are potentially getting enough physical activity through planned exercise and sports, they may still be at increased risk for cancer if they’re spending a lot of their day being inactive and sitting,” she explains.

Dr Friedenreich and her team are still working on collecting and analyzing all the data of this Society-funded supplementary study; therefore, the results will be announced at a later date.

Thanks to you, Canadian Cancer Society-funded researchers are discovering new ways to better prevent, detect, treat and beat cancer. Learn more by reading our Research Impact Report 2014.
Back to the October 2015 issue of Cancer Challengers