Physical activity reduces breast cancer risk by around 20% 

There have been many scientific studies into the role of physical activity on breast cancer occurrence. Although percentages vary, physical activity reduces risk by around 20% overall.

The most significant reduction is seen in pre-menopausal women who do vigorous exercise. One large UK study found very active women had a 23% lower risk of pre-menopausal breast cancer and a 17% lower risk of post-menopausal breast cancer.

Another study found as little as an hour of walking per week helps improve survival rates if you have breast cancer, with maximum benefits found in women who walked for 3-5 hours per week.   

Physical activity also reduces breast cancer risk in men and individuals with a family history or known genetic susceptibility to breast cancer, such as BRCA mutation carriers. A recent study of women with a family history of breast cancer found they had a 20% lower risk if they were physically active compared to genetically susceptible women who were inactive.   

Physical activity reduces breast cancer recurrence and increases survival. 

Physical activity reduces breast cancer recurrence by 20-30% and the mortality risk in diagnosed patients by over 40%. One review that compared women diagnosed with breast cancer doing the least physical activity to those doing the most found that physically active women had a 40% lower risk of breast cancer mortality and a 42% lower risk of mortality from any cause.   

How does physical activity lead to a reduction in breast cancer risk? 

Physical activity affects our bodies in many ways. It plays a part in how we can break down and use our food as energy, how our hormones act and even how our immune system functions. There are several ways that physical activity can reduce breast cancer risk including:  

• Reducing the levels of circulating sex hormones:  High levels of circulating sex hormones, especially oestrogen (and other proteins that help it function), are associated with an increased female breast cancer development and progression. Compared to those of a healthy weight, overweight post-menopausal women have higher levels of oestrogen. Following menopause, the main source of oestrogen is fat cells. Excessive fat can increase oestrogen levels in post-menopausal women, increasing breast cancer risk. Increasing physical activity can help reduce the amount of total body fat a person has.  
• Altering levels of hormones & growth factors that normally help to break down and use our food (metabolise):  Physical activity and less body fat help to control levels of metabolic hormones in males and females, including insulin and the growth factor IGF-1 (growth factors are small proteins that can help to make cells grow; high levels of some growth factors can stimulate out of control growth which can lead to the development of cancer). Both of these hormones help to regulate blood sugar levels. Physical activity improves the body’s response to insulin and reduces insulin resistance, a metabolic disorder that results in high blood sugar levels and high levels of insulin. The condition is associated with an increased risk of breast and other cancers, as well as other diseases such as type 2 diabetes.
• Reduced chronic inflammation and improved immune function: In both men and women, obesity, weight gain and physical inactivity lead to a persistent state of inflammation; this means that the immune system can be active when it shouldn’t be. Physical activity lowers levels of pro-inflammatory factors and increases levels of anti-inflammatory factors.

What you can do 

For general health and well-being, the World Health Organisation recommends at least 150 minutes of moderate, or 75 minutes of vigorous, physical activity weekly. It also recommends doing muscle-strengthening exercises at least twice a week. We recommend doing 300 minutes of moderate physical activity weekly (such as 3x 100 min of gardening), which will help reduce your breast cancer risk even more. But if this isn’t possible – do as much as possible, as any amount is beneficial. And the more you do, the more it helps.

Physical activity doesn’t necessarily mean going to the gym or running a marathon. If you cannot do structured exercise, try to build physical activity into your daily life. Simple lifestyle changes can make a difference. Here are a few suggestions: 

• Walk or cycle to work or when taking your children to school 
• Workout while watching TV 
• When sitting for long periods, try the NHS-recommended sitting exercises 
• Move or stretch at least three to four minutes every hour 
• Take the stairs instead of the escalator or lift
• If you’re on the phone, stand or walk instead of staying seated 
• Stand while participating in a phone conference or webinar 
• Use fitness apps/trackers that remind you to move 
• Incorporate Movement into your morning routine, e.g. “The Scientific 7 Minute Workout.”

Further reading

For more information on physical activity and breast cancer, see our science review.

Read our our blog, How to increase your daily activity without realising for more tips.

Get a copy of our Wellness planner to help your plan and keep track of your minutes, find out more.