[Effects of physical activity on cancer risk and disease progression after cancer diagnosis].

Numerous epidemiologic studies have demonstrated that regular physical activity convincingly reduces risk for colon cancer, probably for endometrium and postmenopausal breast cancer, and possibly for premenopausal breast, prostate, lung, and pancreas cancer. Relative risk reductions range from 10-30%. On the absolute scale about 9-19% of the most frequent cancers can be attributed to a lack of sufficient physical activity. Thus, exercise, as a modifiable health behavior, has a strong potential for primary cancer prevention. Current recommendations call for at least 30-60 min of moderate to vigorous activity daily. Physical activity is also increasingly gaining importance in cancer treatment and is now considered to be feasible, safe, and even recommended in almost all stages of disease. Randomized-controlled trials show that disease- and treatment-related symptoms, such as fatigue, sleep disorders, and depression which sometimes limit quality of life in cancer patients over years, can be reduced by physical activity. For disease-specific and total mortality, clinical studies are not yet available. However, preliminary observational studies with breast, colon, and prostate cancer patients show risk reductions.