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MR Molecular Imaging of Prostate Cancer with a Small Molecular CLT1 Peptide Targeted Contrast Agent
Published on: September 3, 2013
Prostate-specific Membrane Antigen PET: Therapy Response Assessment in Metastatic Prostate Cancer
Felipe G Barbosa1, Marcelo A Queiroz1, Daniela A Ferraro1
1From the Departments of Radiology (F.G.B., M.A.Q., R.F.N., P.R.D., E.C.Z., L.B.C., J.F.G.M., C.A.B.) and Oncology (D.A.B.), Hospital Sírio-Libanês, Rua Dona Adma Jafet 115, São Paulo, SP, CEP 01308-060, Brazil (F.G.B., M.A.Q., R.F.N., P.R.D., E.C.Z., L.B.C., J.F.G.M., C.A.B.); Department of Radiology and Oncology, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil (M.A.Q., D.A.B., J.F.G.M., C.A.B.); and Department of Nuclear Medicine, University Hospital of Zurich, Zurich, Switzerland (D.A.F.).
Abstract:
Therapy response assessment is a critical step in cancer management, leading clinicians to optimize the use of therapeutic options during the course of the disease. Imaging is a pivotal biomarker for therapy response evaluation in oncology and has gained wider use through the development of reproducible data-based guidelines, of which the Response Evaluation Criteria in Solid Tumors is the most successful example. Disease-specific criteria have also been proposed, and the Prostate Cancer Working Group 3 criteria are the mainstay for prostate cancer (PC). However, conventional imaging evaluation in metastatic PC has several limitations, including (a) the inability to detect small-volume disease, (b) the high prevalence of bone (nonmeasurable) lesions at imaging, and (c) the established role of serum prostate-specific antigen (PSA) levels as the biomarker of choice for response assessment and disease progression. In addition, there are an increasing number of newer treatment options with various effects on imaging features. Prostate-specific membrane antigen (PSMA) PET has improved patient selection for newer treatments, such as metastasis-directed therapy (MDT) or radionuclide therapy. The role of PSMA PET in response assessment for many metastatic PC therapeutic options (MDT, androgen deprivation therapy, chemotherapy, radionuclide therapy, and immunotherapy) is an evolving issue, with emerging data showing good correlation with PSA levels and clinical outcome. However, there are specific implications of each therapy (especially androgen deprivation therapy and immunotherapy) on PSMA expression by PC cells, leading to potential pitfalls and inaccuracies that must be known by radiologists. Despite some limitations, PSMA PET is addressing gaps left by conventional imaging methods (eg, CT and bone scanning) and nonimaging biomarkers (PSA levels) in metastatic PC therapy response assessment, a role that can be improved with advances like refinement of interpretation criteria and whole-body tumor burden quantification.© RSNA, 2020See discussion on this article by Barwick and Castellucci.
