Renal Mass Biopsy Prior to Surgical Excision: Practice, Diagnostic Performance, and Impact on Management in the UroCCR Registry (Ancillary Study No. 118).

Background and objective: A renal mass biopsy (RMB) is not systematically recommended before surgical excision of a renal mass, although it has demonstrated elevated accuracy in determining renal masses with low morbidity. Our aim was to determine the diagnostic accuracy of an RMB, the clinical and tumoral factors associated with RMB practice, and the impact of an RMB on renal cell carcinoma management in a contemporary prospective national registry-UroCCR (2010-2021). Methods: We identified all patients with a single renal mass (pT1-4 N0-2 M0 or benign) who were treated surgically and stratified them according to the performance of a prior RMB. Patients treated by active surveillance, percutaneous ablative treatment, or stereotaxic radiotherapy were excluded. Diagnostic accuracy of an RMB was determined in the RMB group. Clinical and tumoral factors associated with the practice of RMBs were analyzed using logistic regression. Key findings and limitations: In total, 9283 patients were included, who presented 1594 tumors (17%) with a prior RMB. RMBs were 92.4% contributive. The correlation between an RMB and excision in the determination of benign/malignant disease, histological subtype, and grade are, respectively, 96.9%, 86.4%, and 52.6%. The impact of an RMB versus no prior RMB was determined according to the rate of surgical excision for benign lesion and the rate of partial nephrectomy (63.9% vs 57.8%; Conclusions and clinical implications: An RMB is performed rarely when its diagnostic performance is high. A prior RMB significantly changes the management of localized renal masses, with fewer surgical procedures for benign renal masses and conservative treatment in a higher proportion of patients. Patient summary: In a large and contemporary registry, we demonstrated that a renal mass biopsy has excellent diagnostic accuracy, significantly reduces renal surgery for benign masses and low-grade/stage renal cell carcinoma, and increases conservative surgical excision.