Exercise Can Help Repair Chemotherapy-Damaged Immune Systems in Breast Cancer Survivors

Exercise after chemotherapy for breast cancer boosted the activity of infection-fighting T cells in women who worked out regularly, according to data from a study conducted at Penn State. These findings indicate that exercise can help restore immune systems damaged by anti-cancer drugs, which destroy healthy as well as malignant cells.

Women between the ages of 29 and 71 were assigned to an exercise group (28 women) or a non-exercise group (21 women). In the intervention arm, women began the exercise routine usually within a month of completing post-surgical therapy. All exercisers followed a similar regimen—stretching to warm up, use of Flexbands for resistance training, and an aerobic activity of their choice: treadmill, exercise bike, or walking. In the exercise group, each woman was paired with a kinesiology intern who served as a personal trainer.

“For the first three months, the women worked out with the trainers at our clinical research center three times a week for about 60 to 90 minutes, at a level the trainers determined was appropriate,” said Andrea Mastro, Ph.D., professor of microbiology and cell biology at Penn State in University Park, PA. “We designed an exercise program that could be done without a gym so that during the second three months, participants had the option of working out at home.”

Testing was conducted before the intervention, at three and six months. Measurements for some immune functions improved; exercisers showed more activated lymphocytes than non-exercisers. In addition, concentrations of IFN-a, an inflammatory substance that indicates trauma (e.g., from treatment), decreased in exercisers but increased in non-exercisers during the first three months. Another assay suggested that lymphocytes damaged or killed by therapy were replaced with new and responsive lymphocytes—which divide to create more invader-fighting cells in response to foreign substances—more quickly in exercisers.

“We know that chemotherapy-induced decreases in T cells can persist for many years, and data from the literature suggest that, in the period immediately following chemotherapy, the surviving T cells may be weakened as well,” Mastro said. “That’s why we’re pleased to find evidence that appropriate exercise can help a breast cancer survivor’s immune system bounce back after therapy.” She noted that during the recruitment phase, some women said that their doctors had counseled them not to exercise after therapy.

Additional test results showed improvements in various physical functions such as endurance, upper-body strength (grip strength, biceps, triceps), and maximal oxygen intake (VO2max). For women who exercised throughout the program, the physical function measures were better at six months than at three months. On a standard questionnaire, exercisers also scored higher on overall quality of life, social well-being, and experienced lower fatigue levels than the non-exercisers. There were no differences in results between women who exercised at home or at the research center.

Most exercisers preferred to continue with the personal trainers at the research center. Women who chose to work out at home kept an exercise log, which they discussed with the trainer during telephone interviews or weekly visits to the Penn State campus. During the first three months, compliance with the exercise regimen was about 82%, dropping to 76% during the second three-month period. According to feedback, distance from the university was a factor in the dropout rate.

There were no significant differences between the two groups in education, cancer treatment or stage, age, overall health, body mass index, or diet. In both groups, equal numbers of women had lumpectomy or mastectomy, most of the women had the same chemotherapy followed by radiation therapy, and most reported doing little if any regular exercise before diagnosis. Among those who had exercised before their diagnosis, walking was generally the activity of choice. The study excluded women who had other serious health conditions or took drugs that could affect the immune system.

Another study, conducted in a similar population by Canadian researchers and published in the Journal of Applied Physiology, also found that exercisers had a greater percentage of activated T cells. Although that research was conducted for three months rather than six and examined aerobic conditioning rather than resistance training, Mastro considers the two studies complementary.

As a follow up, Mastro hopes to conduct a retrospective study of breast cancer survivors to determine whether their immune systems are still depressed five years after treatment.

SOURCES:
“Era of Hope” Department of Defense Breast Cancer Research Program meeting, June 9, 2005, Philadelphia, PA
Journal of Applied Physiology, April 2005

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