Objective: To determine whether use of renal mass biopsy may be associated with a reduction in surgery for patients with small, localized renal cell carcinoma (cT1aN0M0), especially among older patients and patients with greater comorbidity burden. Methods: A total of 106,258 patients with cT1aN0M0 renal cell carcinoma from 2004 to 2015 were analyzed in the National Cancer Data Base. Multivariable logistic regression identified independent associations with nonsurgical management, receipt of biopsy, and pathologic upstaging. Marginal effects were derived by age and comorbidity. A sensitivity analysis was conducted in years identifying patients undergoing active surveillance (2010-2015). Results: There was increased use of biopsy (8.0%-15.3%) and nonsurgical management (11.7%-15.6%) over time. Biopsy was significantly associated with use of nonsurgical management (OR 4.80 [95%CI 4.58-5.02], P <.001) as well as active surveillance (OR 1.87 [1.69-2.07], P <.001) in the sensitivity analysis. Individual predicted probability of undergoing nonsurgical management ranged from 3% to 92% (median 31.4% with use of biopsy) and increased with age and comorbidity. Pathologic tumor upstaging (≥pT3a) occurred more frequently for patients receiving biopsy compared to no biopsy (5.8% vs 3.3%, P <.001). After adjustment, biopsy remained a statistically significant predictor of upstaging (OR 1.31 [95%CI 1.24-1.38], P <.001). Conclusion: Overall, biopsy demonstrated a strong, independent association with reduced use of surgery for cT1aN0M0 kidney cancer, especially with increasing age and comorbidity. The potential association of renal mass biopsy with upstaging warrants caution, but it is uncertain whether it impacts prognosis relative to true perinephric fat invasion.
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