CXCR4 and cancer: This observation indicated that the cyclam group was most sensitive to maintain high affinity to CXCR4, and that (radio)halogenation on the phenyl moiety was a potentially promising approach to introduce radiobromine (76Br/77Br) or radioiodine (123I/124I/131I) for targeted PET/SPECT imaging or radionuclide-based targeted-treatment of CXCR4-positive cancer.