Research clearly shows that being physically active can reduce a person’s risk for several common types of cancer, but understanding what constitutes “exercise” is often lost in translation, a new report shows.
Jennifer Irvine Vidrine, PhD, and colleagues from The University of Texas MD Anderson Cancer Center in Houston surveyed 800 women age 18 and older, and found the majority of women in the United States fail to meet the American Cancer Society minimum recommendations of 30 minutes of moderate exercise five days per week, despite their belief that they do achieve it.
The study, published in the peer-reviewed Journal of Women's Health also found that when it came to healthy lifestyle choices, poor women and those with less education had greater discrepancies between what they reported doing in their daily lives to help prevent cancer and actually engaging in such behaviors.
But what does it really mean when the experts tell people to get 30 minutes of physical activity per day? Do I have to break a sweat and feel my heart pound or does gardening or washing the dishes count? What if I only get 20 minutes in, does that matter?
“I don’t think we have done enough as a research community to answer these questions,” says Kate Wolin, an Associate Professor of Public Health Sciences at Loyola University in Chicago, who researches the role of physical activity and obesity in cancer prevention and post-diagnosis outcomes.
Wolin acknowledges that researchers have convincing evidence to show that as the amount of exercise goes up, the risk goes down for many forms of cancer, including colon, postmenopausal breast and endometrial cancers. But it’s not all together clear as to whether or not exercise can stave off all cancer types or just some.
Scores of studies also show physical activity is associated with decreased risk of cancer mortality with these common cancer types. Exercise may lower the risk of advanced prostate cancer too.
However, she notes in different studies and for different cancer types the amount of exercise a person needs to alter their risk changes significantly.
For instance, some studies, including one led by Wolin, found that walking 30 minutes per day five times a week was sufficient to reduce risk for colon cancer, but not all studies say that.
“On average, more is better and risk seems to go down with about 30 minutes of moderate intensity activity, like walking. But [30 minutes] isn’t a magic number. You may get some risk reduction with less, but you also get greater prevention benefit from more, she wrote in a Cancer Prevention Research & Policy Blog post.
Another factor emerging from research seems to suggest that when a person exercises may also matter.
Researchers have identified several key hormone-associated events that are connected with breast cancer risk, such as a female’s first period, pregnancy and menopause. Research over recent years has examined whether activity at key time points is differentially important.
What they have discovered is that no matter when you start exercise improves your health, but regular activity over a person’s life offers the most cancer protection.
“This [information] has important public policy implications, particularly in light of the declining activity rates of U.S. children and cuts to school based physical education classes and recess time,” said Wolin. “Cancer prevention is not just for adults, but matters across our entire lifetime.”
Lynette Summerill is an award-winning writer and Scuba enthusiast who lives in San Diego with her husband and two beach loving dogs. In addition to writing about cancer-related issues for EmpowHER, her work has been seen in publications internationally.
"Lifestyle and Cancer Prevention in Women: Knowledge, Perceptions, and Compliance with Recommended Guidelines," Jennifer Irvin Vidrine, Diana W. Stewart, Stephen C. Stuyck, Jo Ann Ward, Amanda K. Brown, Courtenay Smith, and David W. Wetter. Journal of Women's Health. June 2013, 22(6): 487-493. doi:10.1089/jwh.2012.4015.
“Leisure-time physical activity patterns and risk for colon cancer in women.” Wolen KY, Lee IM, Colditz GA, Glynn RJ, Fuchs C, Giovannucci E.. Int J Cancer 2007 Dec 15;121)12)2776-81.
Free article at http://www.ncbi.nlm.nih.gov/pubmed/17722094
What we do know and don’t know about physical activity and cancer. Kate Wolin, World Cancer Research Fund International.
Make Exercise Work for You. American Cancer Society (Recommendations). Jan. 12, 2012.
Reviewed August 6, 2013
by Michele Blacksberg RN
Edited by Jody Smith