The Effect of a Home-Based Exercise Intervention on Metabolic Syndrome and Breast Cancer Risk in African-American Women

TON - March 2017, Vol 10, No 2

Cape Town, South Africa—Breast cancer rates are increasing worldwide, paralleling increases in type 2 diabetes, obesity, and metabolic syndrome (MetS). According to Lucile L. Adams-Campbell, PhD, epidemiologist, Georgetown Lombardi Comprehensive Cancer Center, Washington, DC, mortality from these and other diseases is still higher among African-American populations than white populations, regardless of incidence rates. “So that’s where we have to intervene,” she said at the American Association for Cancer Research International Conference on New Frontiers in Cancer Research.

MetS represents a cluster of components associated with an increased risk for cardiovascular disease and includes several risk factors for breast cancer, such as central obesity, hypertension, hyperglycemia, and low high-density lipoprotein cholesterol. Weight gain and obesity are associated with an increased risk for postmenopausal breast cancer, whereas a higher body mass index is associated with a lower risk for premenopausal breast cancer.

“The majority of black people in the US are obese, and something has to be done about that,” said Dr Adams-Campbell. Although the overall incidence of breast cancer in the United States is slightly higher among white women than among black women, the numbers are beginning to equalize, she noted. And the increase in obesity among black women could be a major contributor to this trend.

Study Design

Dr Adams-Campbell and her co-investigators hypothesized that lifestyle interventions may improve the MetS profile and reduce breast cancer risk among black women with MetS who are at an increased risk for breast cancer. This risk measurement was based on the Contraceptive and Reproductive Experiences model, which allows researchers to estimate an African-American woman’s risk of developing invasive breast cancer.

The randomized, controlled FIERCE (Focused Intervention on Exercise to Reduce Cancer) trial compared the impact of a supervised facility-based exercise program and a home-based exercise intervention on obesity, MetS components, and known breast cancer biomarkers in sedentary, postmenopausal, metabolically unhealthy African-American women at increased risk for breast cancer. More than 1500 black women aged 45 to 65 years were screened, and a total of 213 participants were randomized to the trial over a 6-month period.

Seventy-three women were enrolled in the supervised facility-based exercise arm; they reported to a facility 3 times per week for 6 months, for a total of 75 to 150 minutes per week of exercise. Participants in this group kept an exercise diary and made no dietary changes.

A total of 69 women in the home-based exercise group exercised 30 to 45 minutes per day, 4 days per week, over the 6-month study period. They were encouraged to take 10,000 steps a day, and participants received weekly encouraging text messages, or “goal motivators.” Members of this cohort also kept an exercise diary and made no dietary changes.

The control arm was comprised of 71 women. Members of this group also received weekly text messages but were told to keep up their current daily activities and exercise habits, with no changes in diet.

“We only wanted to focus on the impact of exercise. And it’s important to note that smoking is not a big issue in black women, as we’ve seen in numerous studies,” Dr Adams-Campbell said.

Home-Based Intervention Shown More Effective

The data revealed that the home-based intervention arm had more favorable changes in metabolic components compared with the supervised and control groups, Dr Adams-Campbell reported.

“What’s interesting and bothersome at the same time is that the home-based group had a mean weight loss of 12 pounds at 6-month follow-up, but the supervised and control groups gained weight,” she said.

The home-based group also experienced more positive changes in diastolic blood pressure than the supervised group, and it was the only arm to experience a drop in serum triglycerides, for an approximate 20% overall change in MetS components from baseline. Both the home-based and the supervised arms improved in MetS overall, but supervised participants had lower study adherence compared with the home-based participants.

“In this trial, the home-based intervention group, overall, was more effective in improving anthropometric and metabolic syndrome components linked to breast cancer. Obesity is a major contributor to many diseases and cancers, not just breast cancer, so if we can make an impact on obesity, I think that will be very important,” said Dr Adams-Campbell.

She said these findings suggest broad public health utility in addressing lifestyle interventions among black women.

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