Exercise Reduces Cardiovascular Risk in Nonmetastatic Breast Cancer Patients

The incidence of cardiovascular events is reduced with increasing physical activity among women with nonmetastatic breast cancer, according to a new prospective study.

“Improvements in screening and adjuvant therapy have led to significant reductions in cancer-specific mortality in women with nonmetastatic breast cancer,” wrote study authors led by Lee W. Jones, PhD, of Memorial Sloan Kettering Cancer Center in New York. “With continual improvements in cancer outcomes, these patients are becoming increasingly susceptible to noncancer competing causes of mortality, particularly cardiovascular disease (CVD).”

Though much evidence links exercise to reductions in cardiovascular events in other settings, little is known about its effects specifically in nonmetastatic breast cancer patients. The new study prospectively examined the links between exercise and risk reduction in 2,973 women participating in two registry-based regional cohort studies.

The researchers used a questionnaire to assess leisure-time recreational physical activity, measured in metabolic equivalent task-hours per week (MET-h/wk). The results were published online ahead of print in the Journal of Clinical Oncology.

The study had a median follow-up period of 8.6 years, during which time there were 203 newly diagnosed cases of coronary artery disease, 307 cases of heart failure, and 862 total CVD events.

In an analysis adjusted for age, the relative risk of cardiovascular events declined across increasing quartiles of physical activity. With the lowest quartile as the reference group, each increasing quartile had a risk ratio for cardiovascular events of 0.83, 0.72, and 0.57, respectively (P < .001 for trend).

In models adjusted further, there remained a strong inverse relationship between exercise and reduction in risk. Compared with those with ≤ 2 MET-h/wk, the adjusted hazard ratio for all cardiovascular events was 0.91 for 2.1 to 10.3 MET-h/wk; 0.79 for 10.4 to 24.5 MET-h/wk; and 0.65 for > 24.6 MET-h/wk. This was similar specifically for coronary artery disease and for heart failure.

Patients who adhered to national guidelines for adult patients with cancer, which specify at least 9 MET-h/wk, had a 23% reduction in the risk of cardiovascular events. Again, similar reductions were seen specifically for heart failure and CVD.

“Exercise is associated with substantial, graded reductions in the incidence of CVD events, the predominant cause of premature morbidity and mortality in women with nonmetastatic breast cancer,” the authors concluded. “These findings are of immediate clinical importance given the large and rapidly growing population of breast cancer survivors at high risk of late-occurring CVD.”