Breast Cancer: Studies Prove Exercise Makes a Difference

Exercise and Power Walking
Exercise and Power Walking. Photo © National Cancer Institute

When it comes to breast cancer, your weight does matter. How you spend your leisure time also matters. Are you active or inactive? Exercise can make a big difference!

This past year, three studies evaluated the impact of being overweight and getting breast cancer, as well as having a recurrence after being treated for breast cancer.

Study 1: Cancer Incidence in those who Spend Most Leisure Time Sitting

An article published in Cancer Epidemiology, Biomarkers, and Prevention, reported on a study that indicates women spending much of their non-work time sitting may be putting themselves at risk of breast and ovarian cancers.

Data analysis of 69,260 men and 77,462 women, with no prior diagnosis of cancer, enrolled in the American Cancer Society Cancer Prevention Study II Nutrition Cohort found the following:

  • Between 1992 and 2009, 18,555 men and 12,236 women were diagnosed with cancer.
  • Women were more likely to develop invasive breast cancer or ovarian cancer if they spent longer times sitting.
  • No such link was found between the length of time men spent sitting and cancer.
  • More research needs to be done to determine why women were more likely to develop cancers than men as a result of spending long times sitting.

Study 2. Weight Gain after a Diagnosis of Breast Cancer

Researchers from Johns Hopkins Kimmel Cancer Center in Baltimore, MD confirmed that women who had been diagnosed and treated for breast cancer, especially those who had chemotherapy, tended to put on more weight during a four-year  follow-up period than women who were not diagnosed with breast cancer.

Previously, studies have found that women who have survived breast cancer and go on to gain weight are at increased risk of having their cancer return.

The study, which was published in Cancer Epidemiology, Biomarkers & Prevention, shared that the Johns Hopkins research team study included 303 breast cancer survivors and 307 women who had never had breast cancer during the years between 2005 and 2013.

All women were required to complete a questionnaire at the beginning of their participation in the study, and then the research team followed them up after four years. About one-quarter of the women participating in the study were premenopausal. A majority of the women in the study were white.

Study Findings:

  • In women diagnosed with breast cancer, 21% of them put on at least 11 pounds over four years; only 11% of the cancer-free women had this much of a weight gain in the same four-year period.
  • Those participants who finished chemotherapy within five years of the study were 2.1 times more likely as those who did not have breast cancer to gain at least 11pounds.
  • The study considered other things that might result in weight gain that included: age, pre or post menopause status and how physically active the participants tended to be. However, the relationship between breast cancer and weight gain was still significant.

Study 3: Impact of Vigorous Exercise on Body Fat in Postmenopausal Women

Recently an article in JAMA Oncology covered the findings of a year-long clinical trial, the Breast Cancer, and Exercise Trial in Edmonton, Alberta.

The trial measured the outcomes when 400 postmenopausal women, who were previously inactive, and had a body mass index of between 22 and 40, began a regimen of 300 vs 150 minutes a week of vigorous aerobic exercise.

Study authors shared, “A probable association between physical activity and postmenopausal breast cancer risk is supported by more than 100 epidemiological studies.”

Dr. Friedenreich, the author of the study, stated, “In previously inactive postmenopausal women, a 1-year prescription of moderate to vigorous exercise for 300 minutes/week was superior to 150 minutes/week for reducing total fat and other fat measures, especially in obese women.

These results suggest an additional benefit of higher-volume aerobic exercise for possibly a lower risk of postmenopausal breast cancer.”

Obesity is a risk factor for getting breast cancer. It is a risk factor that can be reduced or eliminated through exercise and diet.

If you need help managing your weight after breast cancer treatment, get help in doing so. Being on hormone therapy, to prevent a recurrence, may cause weight gain. The answer is not to stop taking hormone therapy. The answer is to get referrals from a member of your cancer care team for a nutritionist and an exercise program for women on hormone therapy.

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