And, given the relatively small tumour volume (i.e., PSMA-positive load) in brain, the “sink effect” will not occur, as this has been shown only to occur in patients with very high tumour loads (i.e., diffusely metastasized prostate cancer, with total PSMA-positive tumour load >1355 mL).36 This evidence concerns the gene FOLH1 and prostate carcinoma.