The role of physical activity in the prevention and rehabilitation of breast cancer

Abstract

The inverse relationship between physical activity and breast cancer risk has been confirmed by several epidemiological and case control studies. But the use of different test methods makes it difficult to come to a unified statement and a conclusive evaluation as to how much exercise is required. However, risk reduction of breast cancer seems to be between 30 and 40% amongst women who engage in daily and leisure time activities. Exercise has marked effects on many different systems of the human body that may reduce cancer risk, e.g. endogenous hormones, energy balance, body composition, immune function, DNA repair and antioxidant defense. These effects vary according to type, frequency, intensity, and duration of physical activity. The American Cancer Society recommends to engage in moderate to vigorous physical activity at least 4 h a week to reduce the risk of breast cancer. In addition to the apparent role of exercise in primary prevention of breast cancer, there is growing interest in and evidence for its usefulness during and after breast cancer treatment. Exercise may reduce the probability of recurrence and enhance survival. The mechanisms are supposed to be similar to those occurring in primary prevention. In addition, the effects on psychosocial factors and fatigue improve quality of life after the diagnosis. The greatest benefit occurred in women who performed moderate physical activity 3-5 h per week. © 2006 S. Karger GmbH.