Breast Cancer & Physical Activity: What’s the 4-11?

Posted by Liz on Oct 7, 2013 in breast cancer | 0 comments

Want to reduce your breast cancer risk? According to new study findings published in Cancer, Epidemiology, Biomarkers & Prevention, at least an hour of moderate to vigorous daily activity may significantly reduce breast cancer risk in postmenopausal women. That’s just an hour a day or at least seven hours a week.

However, is it really that simple? Moreover, are there other factors at play that influence risk such as hormone receptor status, body mass index, weight gain or use of postmenopausal hormones? Notably, all of these have been linked with an increased cancer risk.

Indeed, when the researchers evaluated information provided by over 73,000 women (ages 50-74) over a course of 12 years, they were able to confirm what has eluded medical science for years: even moderate intensity activity, i.e. walking, when conducted daily, can have a major impact on breast cancer risk. Participants were asked to report, via questionnaire, the average number of hours they spent walking, jogging, running, lap swimming, tennis/raquetball, bicycling, doing aerobics or calisthenics and dancing. Assessments were also made on the number of MET hours — metabolic equivalent hours — were expended. Finally, adjustments were made to the findings that accounted for possible confounding factors, things like education, adult weight change and BMI, smoking and alcohol, age at menopause, personal history of breast cysts, hysterectomy or oopherorectomy, family history of breast cancer and finally, use of any type of hormone therapy and if use was current.

On average, women expended 9.5 MET-hours/week, which is equivalent to 3.5 hours/week of moderately paced walking. Additionally, 47% reported that walking was the only recreational physical activity that they participated in. Overall, these women tended to be leaner, more likely to lose or maintain their weight, more likely to drink alcohol and less likely to be current smokers. Importantly, they were less likely to use hormone replacement. And, compared to more vigorous physical activity (>42 MET-hours/week), women who reported walking at least an hour day were found to have a 14% lower risk for breast cancer; their more active peers almost double this – or a 25% lower risk. These findings remained even after the researchers made adjustments for the factors mentioned above – body type, hormonal status and estrogen receptor status.

In a related press release, a senior epidemiologist with the American Association for Cancer Research and a study co-author, Dr. Alpa Patel, points out that “current guidelines recommend that adults should strive to get at least 2.5 hours per week of moderate intensity activity or 75 minutes per week of vigorous intensity activity for overall health.” Yet, less than half of U.S. American women are active at these levels and the researchers note that an even smaller proportion are likely to achieve the higher levels necessary for breast cancer reduction. And yet, just an hour a day of moderate intensity walking can have a positive impact.

I cannot stress this enough: get off of your butts and walk. It doesn’t take a gym membership or a major equipment investment. And, it may actually prevent breast cancer!