(UroToday.com) Neoadjuvant/induction chemotherapy (NAIC) improves survival in patients with muscle-invasive bladder carcinoma (MIBC). On-treatment response assessment aims to detect chemo-(in)sensitive tumors to continue or cease NAIC. They investigated whether FDG-PET/CT could predict response to NAIC and compared to contrast-enhanced CT.
Between 2014 and 2018 they prospectively included 83 patients with MIBC (highrisk cT2-4N0M0 or cT1-4N+M0-1a). Response to NAIC was assessed after 2-3 cycles with FDG-PET/CT (EORTC criteria) and CECT (RECIST1.1 criteria). They assessed prediction of complete pathological response (pCR; ypT0N0), complete pathological downstaging (pCD; ≤ypT1N0), and progression (inoperable tumor/ypN+/M+). The reference standard was histopathology or clinical follow-up. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were calculated.
Pathological response rates were 21% for pCR, 29% for pCD, and 10% progressed. Sensitivity, specificity, PPV, NPV and accuracy of FDG-PET/CT for prediction of pCR were 53%, 75%, 36%, 86%, and 72%. Sensitivity, specificity, PPV, NPV and accuracy of CECT for prediction of pCR were 8%, 96%, 33%, 81%, and 78%. Sensitivity, specificity, PPV, NPV and accuracy of FDG-PET/CT for prediction of pCD were 92%, 34%, 37%, 91%, and 51%. Sensitivity, specificity, PPV, NPV and accuracy of CECT for prediction of pCD were 93%, 55%, 43%, 96%, and 65%. Sensitivity, specificity, PPV, NPV and accuracy of FDG-PET/CT for prediction of progression were 21%, 96%, 71%, 74%, and 73%. Sensitivity, specificity, PPV, NPV and accuracy of CECT for prediction of progression were 5%, 98%, 50%, 67%, and 67%. Higher specificity of CECT for prediction of pCD was significant (p=0.007). In all other analyses, no significant differences between FDG-PET/CT and CECT were found.
In summary, neither FDG-PET/CT nor CECT were highly accurate and response was often overestimated. Our results suggest routine FDG-PET/CT has insufficient predictive power to aid in response assessment compared to CECT and more accurate methods are needed to select patients for continued treatment with NAIC.
Presented by: Sarah Einerhand, PhD Student, Department of Surgical Oncology (Urology), The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Written by: Stephen B. Williams, MD, MS, FACS, @SWilliams_MD on Twitter, Division of Urology, University of Texas Medical Branch, Galveston, TX; Department of Surgery, University of Texas Medical Branch, Galveston, TX during the International Bladder Cancer Network Annual Meeting, September 28-October 1, 2022, Barcelona, Spain