Adverse pathologic features impact survival outcomes for small renal masses following nephrectomy.

PURPOSE: While most small renal masses (SRM) < 4 cm have an excellent prognosis following resection, the impact of adverse T3a pathologic features on oncologic outcomes of SRMs remains unclear. We sought to compare clinical outcomes for surgically resected pT3a versus pT1a SRMs at our institution. MATERIALS AND METHODS: We retrospectively reviewed records of patients who underwent radical or partial nephrectomy (RN, PN) for renal tumors <4 cm at our institution between 2010 and 2020. We compared features and outcomes of pT3a vs pT1a SRMs. Continuous and categorical variables were compared using Student's t and Pearson's chi-squared tests, respectively. Postoperative outcomes of interest including overall, cancer-specific, and recurrence-free survival (OS, CSS, and RFS) were analyzed using Kaplan-Meier method, Cox proportional hazard regression, and competing risk analysis. Analyses were performed using R statistical package (R Foundation, v4.0). RESULTS: We identified 1,837 patients with malignant SRMs. Predictors of postoperative pT3a upstaging included higher renal score, larger tumor size, and presence of radiologic features concerning for T3a disease (odds ratio [OR] = 5.45, 95% confidence interval [CI] 3.92-7.59, P < 0.001). On univariable modeling, pT3a SRMs had higher positive margin rates (9.6% vs 4.1%, P < 0.001), worse OS (hazard ratio [HR] = 2.9, 95% CI 1.6-5.3, P = 0.002), RFS (HR 9.32, 95% CI 2-40.1, P = 0.003), and CSS (HR = 3.6, 95% CI 1.5-8.2, P = 0.003). On multivariable modeling, pT3a status remained associated with worse RFS (HR = 2.7, 95% CI 1.04-7, P = 0.04), but not OS (HR 1.6, 95% CI = 0.83-3.1, P = 0.2); multivariable modeling was deferred for CSS due to low event rates. CONCLUSIONS: Adverse T3a pathologic features portend worse outcomes for SRMs, highlighting the crucial role of pre-operative planning and case selection. These patients have relatively poor prognosis, and should be monitored more closely and counseled for consideration of adjuvant therapy or clinical trials.