GHR and cancer: GHR antagonism suppresses the endocrine, autocrine, and paracrine functions of GH, and this is an important consideration that has particular relevance for cancer on the basis that both systemic and tumor-derived GH contribute to cancer progression.4,47,50 Furthermore, it is quite clear from earlier studies by Lobie and colleagues that GH has differential effects depending on whether the source of GH is pulsatile secretion from the pituitary or secretion from cancer cells or other cells in the tumor microenvironment.