Exercise for breast cancer rehabilitation

Exercise not only relieves the side effects of breast cancer, but can also significantly improve long-term survival.

It is well known that exercise can help prevent cancer (see blog post “Exercise for breast cancer prevention”), but its powerful effects on cancer recovery remain mostly unappreciated.  Just a couple decades ago many clinicians were recommending that cancer patients avoid physical activity, but this has changed.  Research shows that cancer treatment (namely surgery, chemotherapy and radiotherapy) negatively impacts patients both physically and emotionally, and that these negative effects can be addressed through increased physical fitness.

Unfortunately, following breast cancer diagnosis most women actually decrease their levels of physical activity, and these levels typically remain lower than normal for months or years following cancer therapy.  In fact, a new study concludes that: “the vast majority of early breast cancer survivors do not meet national exercise recommendations 10 years post diagnosis”(ref 1).  This is worrisome both from a quality of life perspective and from a survival perspective.

Exercise can be used to counterbalance a wide range of side effects arising from cancer treatment, including pain, fatigue, weight gain, decreased level of physical function, lymphedema, and decreased quality of life.  POST UPDATE: Our clinic Director Lindsay Davey recently contributed to an evaluation of Toronto Rehabilitation Institute’s HEALTh breast cancer exercise program which was shown to improve fitness, quality of life and depression in participants.

Importantly, exercise can also enormously improve long-term survival.  A number of studies have shown that when compared with sedentary women, women who perform regular physical activity after breast cancer diagnosis experience a 24-67% reduction in the risk of death from all causes, and a 50-53% drop in the risk of breast cancer related death (ref 2).

Furthermore, the positive effects of fitness on breast cancer survival appear to be dose-dependent, meaning that patient survival improves with degree of patient fitness (at least up to a point). Figure 1 shows results of a study where 14,000 women with no prior history of breast cancer were followed and examined for cardiorespiratory fitness and incidence of breast cancer related mortality over time (ref 3).  The data clearly demonstrates that risk of breast cancer related death is reduced at higher levels of physical fitness.

Figure 1: The rate of survival free of breast cancer increases with cardiorespiratory fitness level (ref 3).

This dose-dependent effect of exercise on survival not only applies to women with no prior history of breast cancer, but also to breast cancer survivors – and here the results are even more striking. One study examining levels of physical activity post breast cancer diagnosis concluded that compared to women who performed less than 2.8 MET hours per week of exercise, those who had greater levels of physical activity saw a dose-dependent decrease in risk of death from breast cancer (ref 4).  [“MET” (“metabolic equivalent”) is an approximate measure of energy expenditure per hour of an activity.  For example yoga = 3 MET, walking at 4km/hr = 2.9 MET, jogging = 7 MET.]  Specifically, women who performed 2.8-7.9 MET h/wk of exercise had a 35% decreased risk of breast cancer death, those that performed 8.0-20.9 MET h/wk of exercise had a 41% decreased risk, while those that performed more than 21.0 MET h/wk of physical activity saw decreases in risk of breast cancer death by 49% to 89%.

The data supporting exercise therapy for cancer rehabilitation is both strong and striking, and hopefully also motivating.  In an upcoming blog we’ll review some general guidelines on how to use exercise to help treat the side effects of breast cancer treatment and encourage long-term survival.

References:

1. Mason C., Alfano C.M., et al. Long-Term Physical Activity Trends in Breast Cancer Survivors”. Cancer Epidemiol Biomarkers Prev. 2013 Jun; 22(6):1153-1161.
2. Volaklis K.A., Halle M., Tokmakidis S.P. Exercise in the prevention and rehabilitation of breast cancer. Wien Klin Wochenschr. 2013 May 8.
3. Peel  J.B., Sui X., et al. A prospective study of cardiorespiratory fitness and breast cancer mortality. Med Sci Sports Exerc. 2009 Apr; 41(4):742-8.
4. Holick C., Newcombe P., et al. Physical activity and survival after diagnosis of invasive breast cancer. Cancer Epidemiol Biomarkers Prev. 2008; 17(2):379-86.