Radioisotope-labeled target molecules for breast cancer such as 18F-labeled aptamers of Her2/ErbB2 (human epidermal growth factor receptor 2)25, 125I/131I-labeled anti ICAM-1(intercellular cell adhesion molecule-1) antibody26 and 89Zr-Transferrin27, have been developed. Here, ERBB2 is linked to breast cancer.