Exercise may reduce CV events, mortality risk in breast cancer
Among breast cancer survivors, engaging in high levels of physical activity before or around the time of diagnosis may decrease the risk of developing cardiovascular events (CVE) and dying from coronary heart disease (CHD) after receiving cancer therapy, according to a study presented at the American College of Cardiology’s 66th Annual Scientific Session in Washington, DC.
The study included data from a total of 4,015 participants with nonmetastatic breast cancer who were part of the large Women’s Health Initiative study conducted by the National Institutes of Health from 1991 to 2006.
Physical activity was assessed using the metabolic equivalent of task (MET) hours per week, which is commonly used to measure the intensity of, and the amount of energy expended during exercise.
Participants periodically completed PA questionnaires and were subsequently grouped into quartiles according to PA levels: low (<2.5 MET hours per week), intermediate (2.5 to 8.6 MET hours per week), moderate (8.6 to 18 MET hours per week) and high (<18 MET hours per week, or roughly 5 hours of moderate exercise per week).
Researchers compared PA levels with the risk of developing CVE, which included heart failure, stroke and death, in the years after treatment. The median follow-up was 12.7 years.
A total of 342 CVEs and 96 CHD deaths were reported. After adjusting for multiple variables, researchers noted a decreasing trend for CVE and CHD deaths as PA levels increased; hazard ratios (HRs) were 0.59 for CVE (p=0.001) and 0.41 for CHD death (p=0.006) when comparing the highest PA quartile with the lowest quartile. [Okwuosa T, et al, ACC.17]
Compared to the general population, women diagnosed with early-stage breast cancer are at greater risk of developing heart disease. This is due to the cardiovascular damage associated with cancer treatment, including radiotherapy-induced inflammation and the risk of heart failure and arrhythmia seen with chemotherapy drugs. [Cardiol Res Pract 2011;2011:317659; Circulation 2004;109:3122-3131]
“Some of the chemotherapies can cause heart problems because the heart has very limited ability to regenerate, unlike hair can regenerate, for example, so the risk of cardiovascular issues can persist for many years,” said lead author Dr Tochi Okwuosa. “Exercise provides a level of conditioning within our bodies which, even when we’re under cardiovascular stress (such as with cancer treatments) at some later point, helps us tolerate that stress better.”
Researchers acknowledged limitations of the study, such as the use of self-reported physical activity instead of more objective measures. However, findings appear to support the cardiovascular benefits of regular exercise on cancer patients, and it may even improve outcomes or prevent treatment complications in the long run.“Next to a second or recurrent cancer, heart disease is the second leading killer in cancer patients and survivors, so anything we can do to prevent cancer survivors from developing heart disease is very important,” said Dr Okwuosa.