The mechanisms by which physical activity affects cancer development at different sites are similar.13 The insulin/insulin-like growth factor (IGF) axis influences cell proliferation, differentiation, and apoptosis,30 and IGF-1 has an important role in carcinogenesis.31 Physical activity increases insulin sensitivity and decreases C-peptide levels, which improves insulin resistance.32 Thus, regular physical activity may influence cancer incidence and death via the IGF axis. This evidence concerns the gene IGF1 and cancer.