title: Utility of68Ga prostate specific membrane antigen - positron emission tomography in diagnosis and response assessment of recurrent renal cell carcinoma.
abstract: BACKGROUND
  Prostate specific membrane antigen (PSMA) positron emission tomography (PET) is an emerging imaging modality in prostate cancer. However,68Ga-PSMA-PET may also have diagnostic utility in the setting of renal cell carcinoma (RCC). We investigate the differential role of18F-fluorodeoxyglucose (FDG) and PSMA-PET/CT scanning in patients with oligometastatic RCC. In particular, we focus on the utility of PSMA-PET for diagnostic evaluation of isolated or limited metastases planned for local surgery or radiation, as well as the potential utility of PSMA-PET for therapeutic response assessment in patients receiving stereotactic ablative body radiotherapy (SABR).
  
  
  METHODS
  We present a retrospective series of eight patients in which comparative imaging modalities are evaluated against PSMA-PET scanning. FDG-PET and PSMA-PET scans were performed prior to definitive treatment (either surgery or SABR) of limited recurrent disease. Response assessment after SABR was performed with both PET imaging modalities at multiple time points in a subset of four patients.
  
  
  RESULTS
  Prostate specific membrane antigen uptake is typically more intense than FDG in RCC. In all but two cases, one of which was papillary carcinoma, FDG-PET and PSMA-PET are concordant for detection of sites of disease. We demonstrate for the first time the differential kinetics of post-treatment response using PSMA and FDG-PET, with a more rapid metabolic response observed on FDG-PET. Both modalities demonstrate response earlier than morphological appearances on CT or MRI imaging.
  
  
  CONCLUSIONS
  Our series suggests that PSMA shows early promise as a diagnostic and therapeutic response assessment tool in patients with metastatic RCC receiving definitive local therapies.
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.|Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Shankar
authors.initials: S
authors.lastname: Siva
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: Jason
authors.initials: J
authors.lastname: Callahan
authors.affiliation: Department of Radiation Oncology, Princess Alexandra Hospital, Brisbane, Queensland, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Pryor
authors.affiliation: Calvary Mater Hospital, Waratah, New South Wales, Australia.
authors.forename: Jarad
authors.initials: J
authors.lastname: Martin
authors.affiliation: Division of Cancer Surgery, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Lawrentschuk
authors.affiliation: Division of Radiation Oncology and Cancer Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.|Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Hofman
mesh_terms: D000368:Aged; D000954:Antigens, Surface / Q000378:metabolism*; D002292:Carcinoma, Renal Cell / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005710:Gallium Radioisotopes; D043425:Glutamate Carboxypeptidase II / Q000378:metabolism*; D006801:Humans; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging* / Q000473:pathology; D000072078:Positron Emission Tomography Computed Tomography; D012189:Retrospective Studies
chemical_list: D000954:Antigens, Surface; D005710:Gallium Radioisotopes; D043425:Glutamate Carboxypeptidase II
keywords: kidney cancer; metastasis; positron emission tomography; radiotherapy; staging