Due to the small size and high affinity of HER2 affibody that can specifically bind to HER2 receptor both in vitro and in vivo, rapid clearance from blood and non-targeted tissues, ease of structural modification, and selectivity for cancer-related targets, this affibody is suitable as a radionuclide molecular probe and has excellent potential for use in the diagnosis and treatment of cancer (36–41). Here, ERBB2 is linked to cancer.