Exercise Study for Breast Cancer Survivors

Breast cancer survivors with stronger and larger muscles have better overall survival and lower recurrence than women with weaker and smaller muscles. However, the mechanism for this association is currently unknown. A recent study from the investigators has shown that there is an association between the frequency of immune cell types that kill cancer and higher muscle mass and strength, with higher muscle mass and strength correlating with a higher frequency of cancer killing, effector memory, T cells. The investigators thus propose that increasing muscle mass and strength can improve overall survival and reduce recurrence by increasing the number of cancer killing immune T cells. To test this hypothesis, the investigators will recruit 30 breast cancer survivors to an exercise program designed to increase their muscle mass and strength. The program will be optimized to each participant's level of fitness and strength and will be designed by experts in the field. Personal trainers will teach the participants how to exercise and use muscle resistance training equipment using the correct technique and will monitor progress to avoid injuries and to maximize training benefits. The investigators will collect blood (to study immune cell subsets) and measure muscle strength and body composition (to measure muscle mass) for participants before and after the study. The duration of the exercise training protocol is 4 months and participants will be asked to exercise 4 days a week; 2 days at the gym and 2 days at home.