Can endurance sports stimulate immune mechanisms against cancer and metastasis?

Proceeding from a brief historical contemplation of the problematic nature of "exercise and malignancy" a training investigation (running on a treadmill) with animals is presented. By means of the experimental tumor model fibrosarcoma L-1 of BALB/c mice differences in growth, size, and metastatic spreading have been proven depending upon the mode and more significantly on the intensity of training and upon the mode of application and inoculation of tumor cells. Accordingly the best cancer protective effect could be observed when the animals performed a pre- and a post-running training before and after inoculation. More over mechanisms of the acute phase response of human athletes are discussed in relation to possible prophylactic effects on the prevention of infections and on the development of cancer.