Renal tumor biopsy in patients with cT1b-T4-M0 disease susceptible to radical nephrectomy: analysis of safety, accuracy and clinical impact on definitive management.

Renal tumor biopsy was provided in patients candidate to radical nephrectomy for a renal mass ≥4 cm, to evaluate treatment deviation. Between 2008 and 2017, 102 patients with a solid renal mass ≥4 cm with no distant metastases underwent preliminary renal tumor biopsy. We investigated the proportion of patients who proceeded with radical nephrectomy, variables predicting non-renal cell carcinoma (RCC) and concordance between biopsy findings and definitive pathology. Median tumor size was 70 mm (IQR 55–110). Clinical stage was cT1b in 41, cT2 in 33, cT3 in 25 and cT4 in three patients. A median of three (IQR 2–3) renal tumor biopsies were taken with 16/18 Gauge needles in 97% of cases. Clavien grade I complications occurred in five cases. Malignant tumors were documented in 84 patients: 78 RCCs and six non-RCCs. Fifteen biopsies documented oncocytoma and three were non-diagnostic. Grade was reported in 50 RCCs: 42 (84%) were low and eight (16%) high grade. Eighty-three patients proceeded with radical nephrectomy; six non-RCC malignant tumors underwent combined and/or intensified treatment; 13 of 15 patients with oncocytoma did not undergo radical nephrectomy (eight underwent observation). Definitive pathology confirmed diagnosis in all cases. Grade concordance was 84%, considering two tiers (high vs low grade). No preoperative clinical variable predicted definitive pathology. Renal tumor biopsy is a safe procedure that leads to radical nephrectomy in most tumors ≥4 cm. Nonetheless, 20% of patients exhibited non-RCC histology. Renal tumor biopsy should be considered in this setting. [ABSTRACT FROM AUTHOR]