Diagnostic value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography in staging histological subtypes of invasive bladder cancer

This study assessed the diagnostic value of [ 18 F]FDG-PET/CT in staging histological subtypes (HSs) of invasive bladder cancer. In 112 patients with ≥ 75% HS-content, 87% of primary tumours were FDG-avid, 9% were non-assessable (due to high FDG-avid urine), and only 5% were FDG-negative. [ 18 F]FDG-PET/CT altered staging in 20% of patients, predominantly through upstaging, with little variation across HSs or between pure and mixed content. A matched cohort with conventional urothelial carcinoma showed comparable staging-modification rates. Although pathological confirmation was limited to a selected subgroup, these results support [ 18 F]FDG-PET/CT as a complementary staging modality in both conventional and rare bladder cancer subtypes, with potential to improve staging accuracy and treatment planning.