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Can Exercise Reduce Your Cancer Risk?

New research on the role of physical activity in breast cancer.

Key points

  • Compelling new research suggests that vigorous physical activity reduces breast cancer risk.
  • Incorporating physical activity into your routine can be challenging.
  • Reframing the definition of exercise, using SMART goals, and incorporating self-compassion may all help in changing activity level.

Most of us, at one point or another, have probably been told by our doctor that we should be exercising. Researchers have known for some time that regular physical activity can be helpful for maintaining good health, explaining this common recommendation at your regular check-up.

Research has also emphasized the importance of regular physical activity for cancer prevention and the reduction of cancer recurrence1. Until recently, however, these recommendations have been made based on observational studies. With these types of studies, a group of individuals is followed for a period of time and data is collected about their reported exercise habits. The researchers observe over time who develops cancer and who does not and recommendations are made based on the findings. The problem with these observational studies, however, is that these types of studies cannot determine cause and effect. How do we know if it is the exercise that is reducing cancer risk, versus some other explanation?

A recent study published in the British Journal of Sports Medicine2 used a novel method to determine just that. Previous research has suggested that our genes may predict our tendency to be physically active or sedentary. Using a method called Mendelian randomization, researchers in this study used the participants’ genetic information regarding activity level to predict risk of breast cancer and recurrence. This study examined over 130,000 women, some with breast cancer that had spread beyond the local site, some with breast cancer that had not spread, and some without cancer.

What they found was incredible. Women with genetic variants predisposing them to be more active were 41 percent less likely to develop invasive breast cancer, and this was the case largely regardless of menopausal status, tumor type, stage, or grade. The researchers feel they have strong evidence to suggest that increasing vigorous physical activity and reducing time spent sitting are likely to substantially reduce breast cancer risk. The use of Mendelian randomization provides more confidence that these results are related directly to physical activity as opposed to other factors, such as diet.

While this research is interesting, it isn’t likely to make anyone jump up and start exercising if they haven’t been doing it already. Why? Because changing behavior is hard and finding time for movement can be challenging. However, this recent study and others make a compelling case for the role of physical activity in reducing cancer risk and improving overall health. If you're wondering how you might start to reduce your sitting time, the following suggestions may be helpful for increasing your odds of success.

  • Any movement counts

Physical activity doesn’t just happen in the gym. Playing with your kids, dancing around your kitchen, and taking the stairs instead of the elevator are all tools to help reduce your amount of sitting time. Try getting up and walking around during commercials, or if you have a sedentary job, set an alarm to walk around for a few minutes every hour. Exercise may not be your ‘thing,’ and that’s okay—get creative about how you can move your body and it may feel more doable.

  • Do something you enjoy—or at least, something you don’t hate

I spoke with a client once who was determined to start running to increase her fitness. As we discussed it, I asked her if she enjoyed running. "No," she admitted. "I actually hate it." Knowing that forcing herself to do an activity she hated was unlikely to be sustainable, we problem-solved what she felt she could do instead. Her local community center offered free Zumba classes—something that was fun and that she could do with friends—which felt like a much more accessible alternative.

I know I, like many others, am guilty of getting excited about a new routine and then setting the bar too high at first. Inevitably, I end up feeling stuck and frustrated when I can’t make the progress I’d like. SMART goals are a strategy for helping change behavior in a way that increases the likelihood that change is sustainable. Check out my previous post that reviews SMART goals in detail.

  • Be kind to yourself

Changing behavior and developing new routines can be really tough. Rather than beating yourself up if you miss a day of exercise, try practicing a compassionate and understanding approach. Your body needs rest as well as activity and sometimes life just gets in the way. You may also be in a place where regular physical activity may not be possible right now and that's perfectly okay. Focus on progress instead of perfection and you may find your goals a bit easier to meet.


American Cancer Society (2016). Exercise linked with lower risk of 13 types of cancer. Retrieved from:….

Dixon-Suen, S. C., Lewis, S. J., Martin, R. M., English, D. R., Boyle, T., Giles, G. G., ... & Zheng, W. (2022). Physical activity, sedentary time and breast cancer risk: a Mendelian randomisation study. British Journal of Sports Medicine.