Oncological Safety and Diagnostic Yield of Percutaneous Needle-core Biopsies in Upper Tract Urothelial Carcinoma: The UPERCUT Study.

Background and objective: A percutaneous biopsy of suspected upper tract urothelial carcinoma (UTUC) is considered contraindicated due to potential safety concerns. This study evaluated the risk of tumor seeding along the needle track following a percutaneous needle-core biopsy for UTUC, along with diagnostic yield and oncological outcomes.

Methods: We conducted a retrospective multicenter study involving 53 patients who underwent a percutaneous biopsy for upper urinary tract urothelial carcinoma between 2012 and 2022. The primary endpoint was tumor recurrence along the biopsy needle track, assessed through a centralized review of follow-up cross-sectional imaging. The secondary endpoints included biopsy yield, histological concordance in tumor stage and grade compared with final histology in cases of nephroureterectomy, complication rates, and overall oncological outcomes.

Key findings and limitations: The cohort consisted of 60% male patients with a mean age of 69 yr. At diagnosis, 32% had metastatic disease. A biopsy was performed due to diagnostic uncertainty regarding renal cell carcinoma or other diseases, distant metastases, or failed endoscopic biopsy. The median follow-up imaging time was 8.3 mo. Tumor track seeding occurred in one case (1.9%) 5 mo after the procedure. Biopsy yield was 94%, with histological concordance rates of 78% for tumor stage and 100% for grade. Complications occurred in 14.8% of cases, including two (3.7%) cases of obstructive pyelonephritis requiring endoscopic management.

Conclusions and clinical implications: A percutaneous biopsy is a useful diagnostic tool for high-grade invasive upper urinary tract urothelial carcinoma, with a low risk of tumor track seeding. It provides critical histological confirmation, facilitating future research on neoadjuvant systemic therapies.