Many studies have found a link between regular exercise and a lower risk of being diagnosed with breast cancer, as well as a lower risk of breast cancer coming back (recurrence).
As a result, the American Cancer Society and many doctors recommend that women who’ve been diagnosed with breast cancer, as well as those who haven’t, exercise regularly -- about 4 to 5 hours per week at a moderate intensity level. (Brisk walking is considered moderate intensity exercise.) This is about double what the U.S. Department of Health and Human Services recommends per week for adults.
Now a study suggests that regular exercise may increase the life expectancy of breast cancer survivors. This is because exercise lowers survivors’ increased risk of heart disease and type 2 diabetes, along with recurrence.
The research was published online on Jan. 22, 2018 by the Journal of Clinical Oncology. Read the abstract of “Effects of Aerobic and Resistance Exercise on Metabolic Syndrome, Sarcopenic Obesity, and Circulating Biomarkers in Overweight or Obese Survivors of Breast Cancer: A Randomized Controlled Trial.”
Receiving chemotherapy to treat breast cancer increases a woman’s risk of metabolic syndrome; obesity also increases this risk.
Metabolic syndrome is a cluster of health conditions, including high blood pressure, excess body fat, and high cholesterol. In turn, metabolic syndrome increases the risk of heart disease, type 2 diabetes, and breast cancer recurrence.
According to the researchers, women with metabolic syndrome are 17% more likely to be diagnosed with breast cancer, three times more likely to have a breast cancer recurrence, and two times more likely to die from breast cancer.
"Many people don't know the No. 1 cause of death for breast cancer survivors is heart disease, not cancer," said Christina Dieli-Conwright, assistant professor of research at the University of Southern California Division of Biokinesiology and Physical Therapy and lead author of the study.
Exercise can help reverse the individual conditions that make up metabolic syndrome, but research results have been mixed on whether exercise improves metabolic syndrome as a whole entity. So Dieli-Conwright and her colleagues wanted to see how an exercise program affected metabolic syndrome, as well as sarcopenic obesity and insulin levels in women who had been treated for early-stage breast cancer. Sarcopenic obesity means that a person is obese and also has low muscle mass.
The 4-month-long study included 100 women who had been treated for stage 0 to stage III breast cancer less than 6 months earlier. All the women:
- were nonsmokers
- did about 10 minutes of exercise per week
- had a body mass index (BMI) of 25 or higher or had more than 30% body fat
- had a waist circumference larger than 88 cm (34.65 inches)
- had an average age of 53
Overall, 54% of the women were considered overweight and 46% were considered obese; 40% were premenopausal and 60% were postmenopausal.
In addition to surgery to treat breast cancer:
- 11% of the women also had radiation only
- 13% also had chemotherapy only
- 76% also had both radiation and chemotherapy
The women were randomly assigned to one of two groups:
- Exercise intervention group (50 women): The women received three one-on-one exercise training sessions per week with a trainer for 4 months. The exercise program included resistance training with weights and at least 150 minutes of moderate intensity aerobic exercise per week. All the trainers were certified by the American College of Sports Medicine and the American Cancer Society.
- Usual care group (50 women): The women were asked to log and maintain their current exercise habits for the 4 months of the study. The women also wore an accelerometer to measure how far they walked during the study period. After the study was over, these women were offered the same exercise program as the women in the exercise intervention group.
At the beginning of the study, 78% of the women in the exercise group and 76% of women in the usual care group had metabolic syndrome.
At the end of the study, the researchers found that women in the exercise group had significant improvement in health measures compared to measurements taken at the beginning of the study:
- 15% of the women in the exercise group had metabolic syndrome (a decrease of 63 percentage points) compared to 80% of the women in the usual care group (an increase of 4 percentage points)
- women in the exercise group saw their waist circumference go down by about 7 cm; the waist circumference of the women in the usual care group increased by about 2 cm
- blood triglyceride levels in women in the exercise group dropped from 248.1 mg/dL to 151.8 mg/dL; blood triglyceride levels in women in the usual care group increased from 231.8 mg/dL to 233.7 mg/dL
- blood glucose levels in the women in the exercise group dropped from 109.6 mg/dL to 93.0 mg/dL; blood glucose levels in the women in the usual care group increased from 103.3 mg/dL to 108.1 mg/dL
- body fat levels in the women in the exercise group dropped from 37.1% to 33.4%; body fat levels in women in the usual care group increased from 36.7% to 39.9%
- BMI in the women in the exercise group dropped from 33.5 to 28.0; BMI in the women in the usual care group increased from 33.3 to 34.4
- lean muscle mass in the women in the exercise group increased from 53.8 kg to 56.7 kg; lean muscle mass in the women in the usual care group decreased from 53.0 kg to 49.0
All the improvements in the women in the exercise group were statistically significant, which means they were likely because of the exercise program and not just due to chance.
"Exercise is a form of medicine and this study can just add to that knowledge," Dieli-Conwright said.
She hopes to follow up on this study with a larger trial of more than 300 women. She also would like to test different exercise paradigms to create new types of exercise interventions. If women don’t like 150 minutes per week of aerobic exercise, they could try circuit- or interval-type programs, Dieli-Conwright said. So, exercise could be more tailored to a woman’s preferences.
If you’re still recovering from breast cancer treatment, along with being busy with work, household chores, and family matters, finding time to exercise almost every day can seem impossible.
It can help to break up your exercise into 20- or 30-minute sessions that add up to about 4 hours per week. Walking is a great way to start. Maybe you walk 30 minutes before going to work and 20 minutes on your lunch break. You can add a few more minutes by parking farther away from your building or taking mass transit. Or you can make plans to walk with a friend after work -- you’re more likely to stick with exercise if someone else is counting on you. Plus, you can socialize at the same time.
Along with a healthy diet and lifestyle choices, regular exercise is one of the best things women can do to keep the risk of recurrence as low as it can be. This study adds to other research suggesting that regular exercise can help keep your physical and mental health in top shape. No matter how old you are, it’s never too late or too soon to get moving. And once you do start, keep at it!
Visit the Breastcancer.org Exercise section for tips on exercising safely and how to stick to an exercise routine.