ERBB2 and prostate carcinoma: Radiotracer techniques that are target‐specific are highly sensitive (e.g. targeting somatostatin receptors has been widely used for imaging neuroendocrine tumours)69 but may suffer from specificity issues if the target is expressed more generally (HER2).70 Of note, 68Ga‐PSMA PET can be false negative in up to 5% of patients with prostate cancer, due to absent or low expression of PSMA on prostate cancer cells.