A USC study suggests regular exercise could add to the life expectancy of breast cancer survivors because it lowers their heightened risk of cardiovascular disease, Type 2 diabetes and possibly breast cancer recurrence.
"Many people don't know the No. 1 cause of death for breast cancer survivors is heart disease, not cancer," said Christina Dieli-Conwright, lead author of a study published in the Journal of Clinical Oncology on Jan. 22.
Breast cancer has a relatively high survival rate. An estimated 9 out of 10 people who have breast cancer are still alive five years after they were diagnosed, according to the American Cancer Society. The problem, however, is women tend to gain weight during breast cancer treatment.
The new study suggests female breast cancer survivors should engage in a mix of aerobic and resistance exercise to reduce their increased risk for metabolic syndrome -- a cluster of health conditions that includes high blood pressure, excessive body fat and high triglycerides. High triglyceride levels increase the risk of stroke, heart attack and heart disease.
"In breast cancer patients, metabolic syndrome is exacerbated by obesity, a sedentary lifestyle and receipt of chemotherapy," said Dieli-Conwright, an assistant professor of research at the USC Division of Biokinesiology and Physical Therapy.
Women with metabolic syndrome are 17 percent more likely to get breast cancer, three times more likely to experience breast cancer recurrence and two times more likely to die from breast cancer, the study cited.
Exercise improves heart health
The randomized trial included 100 breast cancer survivors who received cancer treatment less than six months prior to enrolling in the study.
The experimental group received three one-on-one sessions per week over four months. The program included resistance training with weights and at least 150 minutes of moderate-intensity aerobic exercise.
When the study started, about 46 percent of the participants were obese, and 77 percent had metabolic syndrome.
After the intervention, 15 percent of those in the exercise group had metabolic syndrome compared to 80 percent in the control group. The women who exercised lost fat and gained muscle.
They also reduced their risk of heart disease. Their blood pressure decreased by 10 percent and their good cholesterol (high-density lipoprotein or HDL) increased by 50 percent.
Inflammation and more
Obesity causes inflammation, which may promote tumor growth and cause cancer recurrence, said Dieli-Conwright, who regularly works with patients from the USC Norris Comprehensive Cancer Center and Los Angeles County + USC Medical Center.
In a previous study, she analyzed blood samples and fat biopsies from 20 obese patients. She found that exercise improved systemic inflammation and reduced inflammation in fat cells.
"Exercise is a form of medicine," Dieli-Conwright said. "Both of these studies support that idea, and we will continue to conduct studies to supplement traditional cancer therapies."
Kyuwan Lee from USC, Nathalie Sami, Thomas Buchanan and Darcy Spicer from the Keck School of Medicine of USC, Kerry Courneya from University of Alberta, Wendy Demark-Wahnefried from University of Alabama at Birmingham, Debu Tripathy from University of Texas MD Anderson Cancer Center, and Leslie Bernstein and Joanne Mortimer from City of Hope also contributed to the study.
The research was completely supported by the federal government through grants totaling $700,000 from the National Cancer Institute (K07CA160718) and the National Center for Advancing Translational Science of the National Institutes of Health (UL1TR001855, UL1TR000130).
Journal of Clinical Oncology