[¹⁸F]fluorodeoxyglucose PET/CT refines staging and treatment selection in high-risk upper tract urothelial carcinoma

To evaluate the incremental clinical value of [¹⁸F]fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG-PET/CT) beyond contrast-enhanced computed tomography (CECT) for primary staging of suspected high-risk upper tract urothelial carcinoma (UTUC).

We conducted a consecutive paired-imaging cohort study of patients with suspected high-risk UTUC undergoing primary staging with both CECT and [¹⁸F]FDG-PET/CT at a tertiary cancer centre between 2013 and 2025. The primary outcome was clinically relevant stage migration, defined as a transition between non-metastatic and metastatic disease, and its impact on multidisciplinary treatment recommendation. Secondary outcomes included diagnostic performance in cases with histopathological verification.

Among 203 patients, [¹⁸F]FDG-PET/CT resulted in stage migration in 45 (22%), predominantly through upstaging (39 patients [19%]), comprising regional nodal upstaging in 19 patients (9.4%) and distant metastatic upstaging in 22 (11%), with both occurring in two patients. [¹⁸F]FDG-PET/CT led to treatment modification in 43 patients (21%). Stage migration was more frequent in the presence of CECT-suspicious lymph nodes (odds ratio 3.4, 95% confidence interval 1.6-7.3). Among the 62 patients with histopathological verification, [¹⁸F]FDG-PET/CT demonstrated significantly higher sensitivity for nodal metastases than CECT (74% vs 33%) with similar specificity (89% vs 86%). Limitations include the retrospective single-centre design and incomplete pathological confirmation, mostly due to neoadjuvant treatment and omission of surgery in metastatic disease.

[¹⁸F]FDG-PET/CT provides actionable staging information beyond CECT in high-risk UTUC, leading to treatment modification in one in five patients and in half of those with CECT-suspicious nodal disease. These findings support selective use of [¹⁸F]FDG-PET/CT in primary staging to refine treatment selection.