Intervention studies in exercise and cancer prevention.

PURPOSE: The aim of this article is to examine the role of exercise randomized clinical trials and other intervention studies in defining the associations between physical activity and cancer prevention.
METHODS: To accomplish this, data from published randomized clinical trials and other intervention studies were reviewed and summarized.
RESULTS: There are few intervention studies that specifically assess the effect of exercise on biomarkers for cancer. Some early work looking at exercise effect on endogenous sex hormones in premenopausal women is relevant to the etiology of several cancers including breast and endometrium, as risk of these cancers is increased in women with high levels of circulating estrogens. Several randomized clinical trials have assessed the effect of exercise on insulin, a potential cancer growth promoter. A smaller number of studies have assessed the impact of exercise interventions on insulin-like growth factor and insulin-like growth factor binding protein. Several small intervention trials have studied the effect of exercise on immune function. Two current randomized clinical trials focused on exercise effects on cancer biomarkers are outlined.
CONCLUSION: Randomized clinical trials provide important information about the effect of exercise interventions on cancer biomarkers and other outcomes relevant to cancer.