Pilot study: use of gallium-68 PSMA PET for detection of metastatic lesions in patients with renal tumour

Handoo Rhee, John Blazak, Chui Ming Tham, Keng Lim Ng, Benjamin Shepherd, Malcolm Lawson, John Preston, Ian Vela, Paul Thomas, Simon Wood

In this study, we prospectively evaluate the diagnostic potential of a gallium-68 (68Ga) prostate-specific membrane antigen (PSMA)-binding ligand and positron emission tomography (PET) in detecting metastatic lesions in patients with renal tumour. The secondary aim was to determine whether the findings would result in the alteration of patient management. Ten patients with renal lesion and potential metastatic disease on conventional imaging were recruited. Patients underwent PSMA PET in addition to standard imaging. Nine patients underwent nephrectomy and 4 patients underwent additional targeted biopsy to provide specimens for histopathological validation. There were 89 pathological lesions on CT, of which 32 were removed or biopsied for histopathological correlation. With PSMA PET, 86 PET avid lesions were identified with 36 samples being available for analysis. Thirty-five of 36 samples were positive for renal cell carcinoma deposits, whilst 1 sample was inconclusive for diagnosis on biopsy. For the histologically confirmed lesions, there were no false-negative PSMA PET lesions; however, CT was false negative in 11. In two patients, surgical strategies were changed based on PSMA PET findings. PSMA PET may potentially have a role in the preoperative staging of advanced renal cell carcinoma as PET detected multiple histologically proven metastatic lesions which were false negative on CT scanning, resulting in change in surgical strategies in some patients. We cautiously support a larger study to confirm these results and to assess the longitudinal impact on patient outcomes. Australia and New Zealand Clinical Trial Registry (ANZCTR), ACTRN12615000854538 .