FDG-PET/CT for Assessing the Response to Neoadjuvant Chemotherapy in Bladder Cancer Patients

Purpose: To determine the accuracy of ¹⁸F-fluorodeoxyglucose with positron emission tomography and computed tomography (FDG-PET/CT) scans in assessing the response to neoadjuvant chemotherapy (NAC) in patients with bladder cancer scheduled to undergo radical cystectomy (RC).

Patients and methods: All patients treated at our center for muscle-invasive bladder cancer (MIBC) were counseled and offered NAC before RC. FDG-PET/CT scans were performed before the initiation of chemotherapy and after completion of the regimen. Patients with disease with complete response to NAC were those who had (pT0) or residual carcinoma-in-situ (pTis) on final pathology. Those who were downstaged from MIBC to non-MIBC were considered to have a chemosensitive tumor. We used percentage reduction in standardized maximum uptake value (SUV_max) from PET/CT scans as our measure to correlate with the final pathology after cystectomy.

Results: Thirty-seven patients with MIBC who underwent NAC followed by RC were included in the final analysis. FDG-PET/CT had 75% sensitivity (89.66% specificity) in identifying those with complete pathologic response with a 100% change in SUV_max, and 83% sensitivity (94% specificity) for the detection of chemosensitive tumors.

Conclusion: FDG-PET/CT can help determine the response of primary tumor to NAC in patients with MIBC and thus can more accurately predict the prognosis of the patients, or potentially the appropriate time for cystectomy.