Physical Activity Associated With Lower Risk of Breast Cancer

Professor Mathieu Boniol PhD International Prevention Research Institute Lyon, Interview with:
Professor Mathieu Boniol PhD
International Prevention Research Institute
Lyon, France What are the main findings of the study?

Prof. Boniol: We conducted a meta-analysis of all prospective epidemiological studies
on physical activity and risk of breast cancer. It includes 37 studies,
so covers more than 4 million women among which more than 100,000 breast
cancer were diagnosed. We showed that when comparing the most active
women (about 20% of the population) to least active women (another 20%
of the population), vigorous physical activity reduce the risk of breast
cancer by 11%. And the good news is that this decline is irrespective of
age, BMI, menopausal status, country,… It is also true for the most
aggressive breast cancer (ER-/PR-). However, we also showed that this
decline is not observed for women taking hormonal replacement therapies,
as if these treatments (which are already infamous for poor efficacy and
increasing the risk of breast cancer) would nullify any benefit from
physical activity. Were any of the findings unexpected?

Prof. Boniol:  The magnitude of the preventive effect of breast cancer from physical
activity is lower than expected. The WHO for example reported that
21-25% of breast cancer could be prevented by physical activity, with a
broad definition of physical activity, this figure was much too
optimistic. However, a 11% decline when the least active women become
very physically active is already quit something: when you compare to
some small benefit of treatments, decreasing risk of breast cancer (and
mortality) by 11% with such a cheap method, it is encouraging. In
particular, physical activity is also known to have beneficial affect on
colorectal cancer, cardiovascular disease, diabetes, weight control,
etc… What should clinicians and patients take away from your report?

Prof. Boniol:  GPs should encourage their patients to practice sport, whatever their
age, whatever their BMI. Vigorous physical activity is most often
promoted as a practice for young and healthy people, and people could
believe that it is not an activity for them because being too old,
having too much weight,… General population should be informed that
irrespective of these (age, BMI, etc) they would benefit from it. So if
a women has not done sport from the age of 20 to 50, it is still worth
starting practicing it. Same thing for women with a high BMI, as they
would also have a benefit from it. What recommendations do you have for future research as a result of  this study?

Prof. Boniol: If our result is confirmed on the negative effect of HRT on the
preventive effect of physical activity, further research could
investigate whether the declining use of HRT (decline observed in
several countries because of poor efficacy and side effect such as
increasing risk of breast cancer) is followed by further improvement of
the beneficial effect of physical activity on breast cancer risk.


Physical Activity, Hormone Replacement Therapy and Breast Cancer Risk: A meta-anlysis of prospective cohort studies

Abstract presented at The 9th European Breast Cancer Conference (EBCC-9)
March 2014

Last Updated on March 20, 2014 by Marie Benz MD FAAD