Human Growth Hormone (GH) and the Growth Hormone Receptor (GHR) play a role in cancer biology, as exemplified by several scientific findings. The GHR was therefore identified as a possible therapeutic target. Our group recently developed a novel radiopharmaceutical product, i.e. 68-Ga-NOTA-somatropin, for selective imaging of the growth hormone receptor (GHR). In this proposed research project, we will investigate the use of this product in the targeted imaging of GHR-overexpressing tumors. The first aim is to quantify the overexpression of the GHR in cancer patient populations (breast, colorectal and prostate cancer) on the tissue and cellular level and determine its impact on cancer formation and progression. The selective binding capabilities of 68-Ga-NOTA-somatropin will then be evaluated in vitro and in vivo. Finally, a one-vial kit formulation will be developed as well as the clinical relevance investigated in patients. If these results are positive, we propose our novel radiopharmaceutical for use in personalized medicine to specifically target GHR-expression as an indicator for therapy with GHR-axis blocking medications.