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 University under the direction of Andrea Mastro, professor of microbiology and cell biology. Mastro's findings indicate that exercise can help restore immune systems damaged by anti-cancer drugs, which destroy healthy as well as malignant cells.
Mastro will present the research at the "Era of Hope" meeting of the Department of Defense Breast Cancer Research Program in Philadelphia, Pennsylvania, on 10 June 2005. The meeting will include presentations by Mastro and other scientists who are developing a better understanding of the role of everyday choices people make about activities such as eating and fitness regimens in causing or preventing disease.
In Mastro's study, women between the ages of 29 and 71 were assigned to an exercise group of 28 women or a non-exercise group of 21 women. Women in the exercise group began the exercise routine within a month of completing post-surgical therapy. All exercisers followed a similar regimen--stretching to warm up, use of flex-bands 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," Mastro explains. "We designed an exercise program that could be done without a gym, and for the second three months, participants had the option of working out at home."
Most of the 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 University Park campus. During the first three months, compliance with the exercise regimen was about 82 percent, dropping to 76 percent during the second three-month period. According to feedback, distance from the campus was a factor in the dropout rate.
Testing was conducted before the intervention, at three months, and at six months. Measurements for some immune functions improved, with exercisers showing more activated lymphocytes than non-exercisers. Additionally, concentrations of an inflammatory substance (IFN-_) that indicates trauma such as that caused by cancer treatment decreased in the exercisers but increased in the non-exercisers during the first three months. Another assay suggested that lymphocytes damaged or killed by cancer therapy were replaced more quickly in the exercise group with new and responsive lymphocytes--those that can respond to foreign substances by dividing to create more invader-fighting cells.
"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.