...that a significant benefit of 177Lu-PSMA has been shown in patients with advanced PSMA-positive metastatic castration-resistant prostate cancer, with a median overall survival of 15·3 months versus 11·3 months for standard care (HR 0·62; 95% CI 0·52–0·74; p<0·001),2 the tone of the discussions around treatment has changed, with some advocating the disruption of the molecular imaging theranostic concept by discarding 68Ga-PSMA-PET/CT for patient selection. Despite PSMA expression in the majority of patients with advanced metastatic castration-resistant prostate cancer, 126 (12·6%) of 1003 patients did not meet the criteria for PSMA-radioligand therapy (no PSMA-positive lesions or ≥1 exclusionary PSMA-negative lesion) in the VISION trial.2 Exposing patients with inadequate PSMA expression on their tumours to a high dose of radiation without therapeutic benefit due to paucity or even total absence of the target violates the concept of primum non nocere (first do no harm) and conflicts with the rules set by national and international regulations regarding radiation exposure and safety. The patients treated with PSMA-radioligand therapy showed even higher prostate-specific antigen response rates than those in the VISION trial (decrease in prostate-specific antigen of 50% or more in 66% vs 46%), but the overall objective response rate was similar (49% vs 51%).4 More sophisticated dosimetric approaches might be developed in the future, but these methods could require multiple single-photon emission computed tomography in combination with CT scans, blood sampling, and calculations intending to secure a minimum tumour dose while staying below critical doses to normal organs.