Renal Mass Biopsy is Associated With Fewer Radical Nephrectomies for Benign or Indolent Disease, Particularly for T1b Renal Masses.

ABSTRACT

INTRODUCTION: How renal mass biopsy (RMB) impacts patient management with T1 renal masses (T1RM) is unclear. We explore the association between RMB and utilization of active surveillance (AS), nephron-sparing interventions (NSI), and radical nephrectomy (RN). METHODS: Data were analyzed retrospectively using the MUSIC-KIDNEY registry. Treatment received was analyzed using a fitted mixed-effects multinomial logistic-regression model. RESULTS: Of 4062 patients, 19.6% underwent RMB. Factors associated with RMB included younger age, higher Charlson comorbidity score, tumor size > 2.0 cm and higher complexity tumors. AS was selected by 88%, 68%, and 27% of patients with benign, indeterminate, and malignant RMB findings. Non-malignant pathology at surgery was significantly (P < .0001) more common without RMB (vs after RMB) 14.8% vs 7.2% of PN and 10.2% vs 1.7% of RN. Patients with T1bRM managed without or with RMB, AS was chosen by 22% vs 34%, NSI by 31% vs 35%, and RN by 47% vs 32% (P = .0027). An interaction between tumor stage (T1a vs T1b) and RMB remained in multivariable analyses accounting for practice-level variation and other confounding variables. The risk-adjusted RN rate for T1bRM was 41.4% without RMB vs 27.8% with RMB; 7.4 RMB are needed to avoid one RN (number needed to treat) for benign or indolent disease. CONCLUSIONS: Treatments received by T1RM patients undergoing RMB are different than when RMB is omitted, based on RMB results and several confounders. T1RM patients benefit from reduction in intervention for non-malignant disease, particularly when RN is planned. For every 7 biopsies of T1bRM performed, one RN was avoided.