Upstaging to pT3a disease in patients undergoing robotic partial nephrectomy for cT1 kidney cancer: Outcomes and predictors from a multi-institutional dataset

Objectives: Surgically treated clinical T1 (cT1) kidney cancer has in general a good prognosis, but there is a risk of upstaging that can potentially jeopardize the oncological outcomes after partial nephrectomy (PN). Aim of this study is to analyze the outcomes of robot-assisted PN (RAPN) for cT1 kidney cancer upstaged to pT3a, and to identify predictors of upstaging. Material and methods: The study cohort included 1,640 cT1 patients who underwent RAPN between 2005 and 2018 at 10 academic institutions. Multivariate logistic regression model was used to assess the predictors of upstaging. Kaplan-Meier curves and multivariable Cox regression analyses were used to evaluate recurrence-free survival and overall survival. Results: Overall, 74 (4%) were upstaged cases (cT1/pT3a). Upstaged patients presented larger renal tumors (3.1 vs. 2.4 cm; P = 0.001), and higher R.E.N.A.L. score (8.0 vs. 6.0; P = 0.004). cT1/pT3a group had higher rate of intraoperative complications (5 vs. 1% P = 0.032), higher pathological tumor size (3.2 vs. 2.5 cm; P < 0.001), higher rate of Fuhrman grade ≥3 (32 vs. 17%; P = 0.002), and higher number of sarcomatoid differentiation (4 vs. 1%; P = 0.008). Chronic kidney disease (CKD) stage ≥3 (OR: 2.54; P < 0.014), and clinical tumor size (OR: 1.07; P < 0.001) were independent predictors of upstaging. cT1/pT3a group had worse 2-year (94% vs. 99%) recurrence-free survival (P < 0.001). Conclusions: Upstaging to pT3a in patients with cT1 renal mass undergoing RAPN represents an uncommon event, involving less than 5% of cases. Pathologic upstaging might translate into worse oncological outcomes, and therefore strict follow-up protocols should be applied in these cases.