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Physical activity may improve cognitive function among breast cancer survivors
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Increased physical activity improved cognitive function among a cohort of breast cancer survivors who were 2 years beyond surgery, according to study results.
“Slowed processing speed can have substantial implications for independent functioning, supporting the potential importance of early implementation of an exercise intervention among patients with breast cancer,” Sheri J. Hartman, PhD, assistant professor in the department of family medicine and public health at Moores Cancer Center at University of California, San Diego, and colleagues wrote.
Hartman and colleagues conducted a randomized controlled trial that included 87 sedentary breast cancer survivors (mean age, 57 years) who had undergone breast cancer surgery a median 2.5 years earlier.
Researchers assigned study participants to a 12-week physical activity intervention (n=43) or a control arm (n = 44). Investigators analyzed objective and self-reported cognition at baseline and at 12 weeks. Objective measurements were based on NIH Cognitive Toolbox, and self-reported measurements were based on Patient-Reported Outcomes Measurement Information System scales.
Results showed significant improvement on the Oral Symbol Digit subscale — a measure of processing speed — among survivors assigned the intervention (beta = 2.01; P < .05). Survivors who were 2 years or less from surgery demonstrated significantly greater improvement on this subscale score (beta = 4; P < .01), whereas those who had undergone surgery more than 2 years earlier demonstrated no significant improvement (beta = -1.19).
Between-group differences in improvement on self-reported cognition suggested potential differences but did not reach statistical significance.
Researchers observed a significant dose response, as higher levels of physical activity appeared associated with greater objective and self-reported cognition among those assigned the exercise intervention.
HemOnc Today spoke with Hartman about the study, the potential implications of the results, and what questions must be explored in subsequent research.
Question: What prompted this study?
Answer: Problems with cognition are common among breast cancer survivors, but there are few evidence-based strategies to improve cognition for these survivors. Increasing physical activity has been shown to improve cognition among adults without cancer, so we wanted to test if increasing exercise would also be helpful for cancer survivors.
Q: How did you conduct the study?
A: We enrolled 87 breast cancer survivors who were self-reporting difficulties with their thinking abilities into a 12-week study. Half of the women were randomly assigned to a physical activity intervention program, and the other half was randomly assigned to a waitlist control arm. The exercise program asked women to wear a Fitbit activity monitor to track their exercise. Data from the monitor were used to provide individual counseling and feedback through phone calls and emails to encourage behavioral change.
Q: What did you find?
A: The intervention program led to about a 100-minute per week increase of moderate to vigorous physical activity among participants in the exercise group compared with about a 5-minute per week decrease in the control group. Women in the exercise group showed more than double the improvement in an objective measure of processing speed — which assesses how fast information can be taken in and used — compared with those in the control group. Taking a closer look at the data, we found greater improvements in processing speed for women who were closer in time to their breast cancer surgery. There also was some indication of benefits for self-reported cognitive abilities, with women in the exercise group reporting three times the improvements as those in the control group. Although there were no statistically significant between-group differences in improvements of self-reported cognition, results were suggestive of potential greater benefits for the exercise group.
Q: What are the clinical implications of the findings?
A: This provides some preliminary evidence that increased physical activity may be beneficial for breast cancer survivors with slowed thinking.
Q: Can you provide some context about the prevalence of cognitive problems among breast cancer survivors?
A: It is estimated that up to 75% of breast cancer survivors experience some cognitive problems. These problems often are mild, but they still can cause difficulties with daily functioning or a person’s ability to return to work. They also can negatively affect mood and quality of life.
Q: Are these results practice-changing or must the benefits of this intervention still be confirmed in subsequent research?
A: These results do need to be confirmed in a longer and larger study, but there are many known benefits of increasing physical activity for breast cancer survivors. They include improvements in quality of life and decreased risk for cancer recurrence. These findings suggest that the benefits may extend to brain functioning, as well. – by Jennifer Southall
Reference:
Hartman SJ, et al. Cancer. 2017;doi:10.1002/cncr.30987.
For more information:
Sheri J. Hartman, PhD, can be reached at UC San Diego Moores Cancer Center, 3855 Health Sciences Drive, Mail Code: 0901, Room 3056, La Jolla, CA, 92093-0901; email: sjhartman@ucsd.edu.
Disclosure: Hartman reports no relevant financial disclosures.