(RxWiki News) Research has demonstrated that physical activity lowers the risk of breast cancer. What hasn’t been clear are the specifics – how long and how intense the exercise needs to be to cut risks. A new study drills down on how exercise can reduce a postmenopausal woman's chances of developing breast cancer.
The formula is pretty easy to remember – an hour a day.
Researchers found that postmenopausal women who walked or exercised vigorously for an hour a day significantly lowered their risks of breast cancer.
Walking cut risks by 14 percent, while vigorous activity such as running or swimming lowered breast cancer risks by 25 percent.
"Walk, jog, run or swim every day."
Alpa Patel, PhD, senior epidemiologist at the American Cancer Society (ACS) in Atlanta, Ga, was the lead investigator of this study.
Dr. Patel and colleagues identified 73,615 postmenopausal women from a large group of 97,785 women between the ages of 50 to 74 years, recruited between 1992 and 1993 to participate in the ACS Cancer Prevention Study-II Nutrition Cohort.
During enrollment, the women completed a questionnaire regarding their demographic (age, race, education, income, etc.), medical and lifestyle issues.
Information gathered included the woman’s weight changes during adulthood, and BMI (body mass index – a measure of body fat), age when children born, age at menopause onset, smoking and alcohol history, among other variables.
The women were asked about the types of physical activity they engaged in and how many hours a week they spent being active.
The time spent in leisure time, sitting watching TV or reading was also recorded and measured.
This information was updated every two years from 1997 and 2009.
During the study period, 4,760 women developed breast cancer. These women were asked about the hormone receptor status of their cancers.
At the beginning of the study, 9.2 percent of the women said they did not participate in any recreational physical activity.
“Physically active women, regardless of the amount, engaged primarily in activities judged to be of moderate intensity (walking, cycling, aerobics, and dancing) rather than vigorous-intensity activities (jogging/running, swimming, tennis/racquetball),” the authors wrote.
Nearly half (47 percent) of the women said walking was their only activity. These women reported they spent about 3.5 hours a week walking at a moderate pace.
The study found that women who walked at least seven hours a week had a 14 percent lower breast cancer risk than did women who walked for 3.5 hours a week.
The most active women who engaged in vigorous exercise for an hour a day had a 25 percent lower risk of developing breast cancer compared to the least active women.
These associations were not altered by a woman’s BMI, weight gain, hormone therapy use or the amount of time spent sitting. The hormone receptor status of the women who did develop breast cancer was not altered by the type or intensity of physical activity.
“Without any other recreational physical activities, walking on average of at least one hour per day was associated with a modestly lower risk of breast cancer. More strenuous and longer activities lowered the risk even more,” Dr. Patel said in a prepared statement. Based on these findings, Dr. Patel says walking should be encouraged among postmenopausal women.
dailyRx News spoke with James Crowell, owner and head trainer of Integrated Fitness in Pittsburgh, about this study. He told us, “I would absolutely recommend activity such as walking each and every day. This keeps our bodies more able to respond to the daily stress that we place on ourselves. Without that activity our body ‘adapts’ to being stagnant and we slowly weaken over time.”
Crowell went on to say, “I believe that virtually everybody has the ability to be active and that a quality workout program should be worked into over time. When you build that consistency you will be amazed how much success you have and how your health metrics improve!"
This study was published October 4 online in Cancer Epidemiology, Biomarkers, and Prevention, a journal of the American Asociation for Cancer Research.
The American Cancer Society funds the creation, maintenance, and updating of the CPS-II cohort. No conflicts of interest were disclosed.