The study included seven castrate patients whose prostate cancer and the presence of lesions had been proven by prostate specific antigen (PSA) test, bone scan, or CT scan. The patients were evaluated using PET scans with the androgen receptor binding agent [18F] fluoro-dihydro-testosterone (FDHT) and the glycolysis imaging agent [18F] 2-Fluro-D-glucose (FDG), as well as the conventional imaging methods (CIM) noted above. The results of all of the techniques (CIM, FDHT PET and FDG PET) were then compared to each other.
Conventional methods detected 59 lesions among the seven patients, indicating areas where the cancer may have spread. FDG PET detected 58 of these abnormalities, while FDHT PET detected 46. FDHT was rapidly absorbed in the majority of metastatic lesions, indicating the presence of functioning androgen receptors in patients with advanced prostate cancer and demonstrating the potential of FDHT to trace the evolving role of androgen receptors in progressive metastatic prostate cancer. Of note is the fact that, in two of the patients who returned for new scans after they had begun testosterone therapy, FDHT uptake was markedly reduced.
The study, which was presented at the Society of Nuclear Medicine’s 50th Annual Meeting, was conducted by Larson and colleagues in the Departments of Radiology and Medicine at the Memorial Sloan Kettering Cancer Center in New York, the Department of Pharmacology and Therapeutics at the Sloan Kettering Institution in New York, and the Department of Radiology at the Washington University School of Medicine in St. Louis, Missouri.