In a study by Irwin et al, published in the Journal of Clinical Oncology, researchers found that women who did the equivalent of at least two to three hours of brisk walking each week in the year before they were diagnosed with breast cancer were 31% less likely to die of the disease than women who were sedentary before their diagnosis.
The study also found that women who increased their physical activity after diagnosis had a 45% lower risk of death compared with women who were inactive both before and active diagnosis.