A recent  study from Dr. Paul T. Williams on International Journal of Cancer describes the benefits of intense physical exercises on breast cancer survival ¹.

Physical activity improves our health conditions reducing the risk of many diseases, such as cardiovascular diseases, diabetes, and cancer. Previous studies linked regular physical exercises, even mild activity, with decreased breast cancer risk ^2,3. Instead, the study reported here points out the importance of an intense physical activity over a mild activity.

Paul Williams from Lawrence Berkeley National Laboratory surveyed 986 breast cancer survivors, 272 runners and 714 walkers.  When the two groups where considered together, breast cancer mortality decreased proportionally to the hours of exercises (23.9% per metabolic equivalents-MET-hours/day). Instead, when the two groups were considered separately, breast cancer mortality was lower in runners than in walkers (66.5% difference), and in runners the mortality decreased proportionally to the hours of exercise (87.4% lower for 1.8 to 3.6 MET-hours/d). There was a correlation with age of death, suggesting that running was more effective in preventing mortality later than earlier in life. Although previous studies correlated BMI and adiposity with breast cancer mortality, in this report neither BMI, education, or diet influence the mortality. The incongruence might be due to the leaner cohort considered here, as pointed out by the same author. Physical activity alters metabolism, influencing blood concentration of different biomarkers used for breast cancer (estradiol, fasting insulin, and C-reactive protein), thus indicating a profound effect on its progression at the metabolic and molecular level.

As Williams discusses in the paper, this study presents some limitations, such as the small number of subjects. Moreover, although this study describes very accurately the information about women’s activity, it lacks some very useful information, such as data on the actual disease, receptor status, invasiveness, metastases or treatment. Given the low rate of mortality in this group, the women reported in this study seem to be a selected set of survivors with a less invasive disease.

Despite these limitations, the study presents for the first time the advantage of intense physical activity over mild activity, suggesting that exceeding the public health recommendations might be better for breast cancer survival, and probably for other health-related issues.

Therefore walking for 30 minutes for 5 days a week might not be enough!

 

1. Paul T. Williams. Significantly greater reduction in breast cancer mortality from post-diagnosis running than walking. International Journal of Cancer, 2014; DOI: 10.1002/ijc.28740
2. Hildebrand JS, Gapstur SM, Campbell PT, Gaudet MM, Patel AV. Recreational physical activity and leisure-time sitting in relation to postmenopausal breast cancer risk. Cancer Epidemiology, Biomarkers, and Prevention, October 2013
3. Lauren E. McCullough, Sybil M. Eng, Patrick T. Bradshaw, Rebecca J. Cleveland, Susan L. Teitelbaum, Alfred I. Neugut, Marilie D. Gammon. Fat or fit: The joint effects of physical activity, weight gain, and body size on breast cancer risk.Cancer, 2012; DOI: 10.1002/cncr.27433