LAUSR

OBJECTIVE To provide insight into the use and staging information on lymph-node involvement added by fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) provides in MIBC patients, based on a nationwide population-based cohort study. PATIENTS AND METHODS We analyzed a nationwide cohort of patients with MIBC without distant metastases, newly diagnosed in the Netherlands between November 2017 and October 2019. From this cohort, we selected patients who underwent pretreatment staging with CT only or CT and FDG-PET/CT. The distribution of patients, disease characteristics, imaging findings, nodal status (cN0 vs. cN+) and treatment were described for each imaging modality group (CT only vs. CT and FDG-PET/CT). RESULTS We identified 2731 MIBC patients: 1888 (69.1%) underwent CT only; 606 (22.2%) underwent CT and FDG-PET/CT, 237 (8.6%) underwent no CT. Of the patients who underwent CT only, 200/1888 (10.6%) were staged as cN+, vs. 217/606 (35.8%) patients who underwent CT and FDG-PET/CT. Stratified analysis showed that this difference was found in patients with cT2 as well as cT3/4 MIBC. Of patients who underwent both imaging modalities and were staged with CT as cN0, 109 of 498 (21.9%) were upstaged to cN+ based on FDG-PET/CT. Radical cystectomy was the most common treatment within both imaging groups. Preoperative chemotherapy was more frequently applied in cN+ disease and in FDG-PET/CT staged patients. Concordance of pathological N-stage after upfront RC was higher among patients staged as cN+ with CT and FDG-PET/CT (50.0% pN+) then those staged as cN+ with only CT (39.3%). CONCLUSION Patients with MIBC who underwent pretreatment staging with FDG-PET/CT were more often staged as lymph node-positive, regardless of cT-stage. In MIBC patients who underwent CT and FDG-PET/CT, FDG-PET/CT leads to clinical nodal upstaging in approximately one-fifth. Additional imaging findings may influence subsequent treatment strategies.