Pathological characteristics of the large renal mass: potential implication for clinical role of renal biopsy

INTRODUCTION: To assess whether patients with a large renal mass, treated by radical nephrectomy (RN), could have benefited from preoperative renal mass biopsy (RMB). The decision to perform partial nephrectomy (PN) for an organ-confined > 4 cm renal mass can be complex. Albeit often feasible, oncologic safety of PN in this cohort is debated. Yet, a significant portion of large renal masses that undergo RN prove benign or indolent, indicating a potential role for RMB to guide nephron preservation. MATERIALS AND METHODS: We queried prospectively maintained databases from three institutions to identify patients who underwent RN for localized > 4 cm renal mass. We excluded patients with nodal or distant metastases. Multivariable analysis assessed how clinicopathologic variables, mass anatomic complexity, and patient comorbidities related to the likelihood of harboring an indolent neoplasm. RESULTS: A total of 702 patients underwent RN for localized > 4 cm renal mass (median tumor size 7.0 cm (IQR 5.5-9.2); 12.8% (n = 90) of patients were diagnosed with oncocytoma/oncocytic neoplasm (n = 27, 3.8%) or chromophobe RCC (n = 63, 9.0%). When stratified by tumor size, indolent tumors comprised 10.1% of 4-7 cm masses, 15.6% of ≥ 7-10 cm masses, and 17.3% of ≥ 10 cm tumors. Upon multivariate analysis, younger age was associated with indolent tumors (p = 0.04, OR 0.97, 95% CI 0.94-0.99). CONCLUSIONS: Approximately 1 in 8 patients with a renal mass > 4 cm harbored benign or low risk indolent potential lesions and were associated with younger age. As such, patients with large renal masses for whom risk trade-offs between PN and RN are unclear, present a unique opportunity for greater utilization of RMB.