Clinical impact of routine second‑opinion reading of [¹⁸F]FDG‑PET/CT in newly diagnosed invasive bladder cancer: A multicentre study in a centralised referral network

PURPOSE: [¹⁸F]FDG‑PET/CT is increasingly used to stage invasive bladder cancer (IBC), resulting in growing demand at tertiary centres for time‑intensive second‑opinion reading of externally acquired scans. However, the incremental clinical value of routine reinterpretation is unclear. We evaluated the clinical impact of second‑opinion [¹⁸F]FDG‑PET/CT reading in a centralised referral network in the Netherlands. METHODS: In this multicentre retrospective diagnostic cohort study, consecutive patients with histologically confirmed high-grade IBC who underwent externally acquired [¹⁸F]FDG‑PET/CT followed by expert second‑opinion reading at two tertiary centres were evaluated. Initial staging reports were compared with second-opinion staging assessments. Clinically meaningful discrepancies were defined as changes in nodal status (cN0 vs. cN+) or distant metastatic status (cM0 vs. cM1 or cM1a vs. cM1b). Treatment recommendation changes directly attributable to second-opinion reading were recorded. RESULTS: Six hundred patients were included. Agreement between initial and second‑opinion reading was high for both nodal and metastatic staging (κ = 0.89 and κ = 0.87, respectively). Clinically meaningful discrepancies occurred in 33 patients (5.5%), resulting in revised treatment recommendations in 22 patients (3.7%). Suspected nodal disease on the initial report was associated with higher odds of discrepancy at second-opinion reading (OR 2.1, 95% CI 1.0-4.4). CONCLUSION: In this multicentre cohort, routine second‑opinion reading of externally acquired [¹⁸F]FDG‑PET/CT for IBC yielded limited incremental clinical impact within a centralised referral network in the Netherlands. These findings suggest that a more selective approach to second-opinion reading, particularly for patients with suspected nodal disease on the initial report, may warrant further evaluation.