AR and neoplasm: A single 18F-FES PET scan failed to show crosstalk with other pathways; therefore, it would be of interest in future studies to add multiple molecular imaging probes to improve the predicted response to palbociclib-based treatment, such as 18F-fluoro-5α-dihydrotestosterone (18F-FDHT)-PET for imaging AR [43] and 18F-FDG PET for imaging the glycolytic metabolism tumour burden [44].