Clinical and preclinical studies have indicated that affibody molecules can provide high sensitivity and specificity for visualizing several targets in cancer xenografts, e.g. human epidermal growth factor 2 (HER2), human epidermal growth factor receptor type 3 (HER3), insulin-like growth factor 1 receptor (IGF-1R), platelet-derived growth factor receptor β (PDGFRβ) and carbonic anhydrase IX (CAIX) using single photon emission computed tomography (SPECT) and positron emission tomography (PET) techniques (Ståhl et al. 2017). Here, CA9 is linked to cancer.