An on-going study at the Dana-Farber Cancer Institute, the Pre-Operative Health and Body Study, evaluates the impact of exercise on human breast cancer cells in an effort to understand how exercise could affect breast cancer risk and prognosis. The study enrolls women as they are diagnosed with breast cancer and assigns them to an exercise group or a control group. Breast tumor tissue is collected at the time of enrollment through a biopsy, and again at the time of breast surgery. The effect of exercise on tumor tissue is assessed by comparing changes in tissue markers over time in patients assigned to the exercise group vs. the control group. Dr. Ligibel’s project will provide a more detailed analysis of the impact of exercise on breast tumor tissue, by studying exercise-induced changes in expression of genes and microRNAs. These evaluations will provide information about the cellular pathways that exercise affects in breast cancer cells, providing insight into how exercise could affect cancer formation and prognosis. The project will also evaluate whether changes in gene expression in breast tumor tissue differ according to patient or tumor characteristics, in order to determine which patients are most likely to derive benefit from exercise interventions.