Aim/Introduction: Radium-223 dichloride has emerged as the only bone-directed treatment option demonstrating an improvement in overall survival (OS) in metastatic castrate resistant prostate cancer (mCRPC). However, there is an urgent need for the identification of reliable molecular imaging biomarkers to non-invasively determine its efficacy (possibly improving patients' selection or identifying responders' after therapy completion). Generally, the FDG avidity is low in treatment naïve prostate cancer, increased in castrationresistant prostate cancer (mCRPC), and almost always present in chemotherapy-refractory mCRPC. Accordingly, FDG-PET/CT may represent an effective tool for measuring disease burden at baseline, performing prognostic stratification and assessing treatment response to radium-223 in mCRPC. Materials and Methods: All mCRPC patients underwent a baseline FDG-PET/ CT for prognostic stratification before radium-223 treatment initiation. Only patients with positive FDG-PET/CT at baseline were subsequently submitted to FDG-PET/CT after two months from radium-223 treatment completion. The following parameters were measured: SUVmax, SUVmean, metabolic tumor volume (MTV), total lesion glycolysis (TLG) per lesion and per patient bases. In patients who underwent post-therapy FDG-PET/CT, Deauville Score, PERCIST and EORTC criteria were applied to evaluate treatment response. Differences between LDH, ALP and PSA levels at the end of therapy with respect to baseline were also calculated (termed deltaLDH, deltaALP and deltaPSA). The correlation between PET- and biochemicalderived parameters with and OS were measured by Kaplan-Meier analyses. Results: 41 mCRPC patients who underwent both FDG-PET/CT scans were included in the final analysis (median interval between the two scans: 213 days). After a median follow-up of 12 months, 23/41 (56%) patients were still alive. At baseline, MTV and TLG significantly predicted long term OS independently from biochemical data. After therapy, deltaPSA, deltaLDH, PERCIST and EORTC scores were the most relevant predictors of OS. When combined, while PERCIST and EORTC classes were able to discriminate different OS in patients with deltaPSA and deltaLDH values within the first tertile including patients with reduction in PSA and LDH, their prognostic power disappeared in the two remaining tertiles in both groups, including patients showing biochemical progression during the course of treatment. Conclusion: FDG-PET/CT can represent a widely available method to directly measure active de-differentiated tumor burden in mCRPC patients' candidates to radium-223, providing prognostic information overpowering biochemical parameters. After treatment it can assess tumorì load reduction particularly in patients included in the first tertile of deltaPSA and deltaLDH. References: None
Role of FDG PET/CT in the prognostic stratification and response assessment of castration-resistant prostate cancer treated with radium-223 dichloride
C Marini;
2019
Abstract
Aim/Introduction: Radium-223 dichloride has emerged as the only bone-directed treatment option demonstrating an improvement in overall survival (OS) in metastatic castrate resistant prostate cancer (mCRPC). However, there is an urgent need for the identification of reliable molecular imaging biomarkers to non-invasively determine its efficacy (possibly improving patients' selection or identifying responders' after therapy completion). Generally, the FDG avidity is low in treatment naïve prostate cancer, increased in castrationresistant prostate cancer (mCRPC), and almost always present in chemotherapy-refractory mCRPC. Accordingly, FDG-PET/CT may represent an effective tool for measuring disease burden at baseline, performing prognostic stratification and assessing treatment response to radium-223 in mCRPC. Materials and Methods: All mCRPC patients underwent a baseline FDG-PET/ CT for prognostic stratification before radium-223 treatment initiation. Only patients with positive FDG-PET/CT at baseline were subsequently submitted to FDG-PET/CT after two months from radium-223 treatment completion. The following parameters were measured: SUVmax, SUVmean, metabolic tumor volume (MTV), total lesion glycolysis (TLG) per lesion and per patient bases. In patients who underwent post-therapy FDG-PET/CT, Deauville Score, PERCIST and EORTC criteria were applied to evaluate treatment response. Differences between LDH, ALP and PSA levels at the end of therapy with respect to baseline were also calculated (termed deltaLDH, deltaALP and deltaPSA). The correlation between PET- and biochemicalderived parameters with and OS were measured by Kaplan-Meier analyses. Results: 41 mCRPC patients who underwent both FDG-PET/CT scans were included in the final analysis (median interval between the two scans: 213 days). After a median follow-up of 12 months, 23/41 (56%) patients were still alive. At baseline, MTV and TLG significantly predicted long term OS independently from biochemical data. After therapy, deltaPSA, deltaLDH, PERCIST and EORTC scores were the most relevant predictors of OS. When combined, while PERCIST and EORTC classes were able to discriminate different OS in patients with deltaPSA and deltaLDH values within the first tertile including patients with reduction in PSA and LDH, their prognostic power disappeared in the two remaining tertiles in both groups, including patients showing biochemical progression during the course of treatment. Conclusion: FDG-PET/CT can represent a widely available method to directly measure active de-differentiated tumor burden in mCRPC patients' candidates to radium-223, providing prognostic information overpowering biochemical parameters. After treatment it can assess tumorì load reduction particularly in patients included in the first tertile of deltaPSA and deltaLDH. References: NoneI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
