18F-labelled anti-HER2 VHHs showed a tumor-to-background and tumor-to-muscle ratio of 13 and 34, respectively, compared to 3 and 10 for 18F-labelled anti-HER2 affibodies, and 2 and 7 for 18F-labelled anti-HER2 diabodies (29). This evidence concerns the gene ERBB2 and neoplasm.