In breast cancer, pituitary and exogenous GH seems to be less involved, while local expression of GH has been shown to have profound autocrine/paracrine effects in breast tissue independent of IGF-I, leading to increased epithelial cell proliferation, and conferring an invasive phenotype on mammary carcinoma cells by affecting epithelial–mesenchymal transition [50, 51]. This evidence concerns the gene IGF1 and breast cancer.