Impact of rhabdoid differentiation on postoperative outcome for patients with N0M0 renal cell carcinoma.

BACKGROUND AND OBJECTIVE: We assessed the aggressiveness of localized renal cell carcinoma (N0M0 RCC) with rhabdoid differentiation (RD) after partial or radical nephrectomy. METHODS: A total of 604 patients with N0M0 RCC who had undergone partial or radical nephrectomy at a single institution were included in this study. Clinicopathological and outcome data on recurrence-free survival (RFS), cancer-specific survival (CSS), and time to recurrence (TTR) were analyzed using Kaplan-Meier methods, log-rank test, univariate and multivariable Cox proportional hazard models, and concordance index. We also evaluated the RFS and CSS in a propensity score-matched cohort to reduce inherent differences. Among the 604 patients, RD was identified in RCC specimens from 24 patients. RESULTS: At the median postoperative follow-up period of 53 months, 58 patients (12 with RD) showed recurrence and 26 patients (7 with RD) had died from RCC. Multivariate analyses showed that RD was an independent risk factor of RFS (hazard ratio 2.81; P = 0.0266) and CSS (hazard ratio 5.18; P = 0.00182). By RD adding to standard risk factors, the concordance indices for RFS and CSS increased 0.77 to 0.79, and 0.76 to 0.79, respectively. Subgroup analysis showed that the presence of RD in RCC specimens was more important for predicting poor RFS and CSS in the early pathological tumor category (≤pT2) subgroup compared to in the advanced tumor category (≥pT3) subgroup. Patients with RD showed a significantly shorter TTR than patients with RCC without RD (7.5 vs. 18 months: P = 0.0150). The propensity score-matched cohort included 24 patients with RD and 24 without RD, of which patients RD showed significantly shorter RFS than those without RD (P = 0.0026). CONCLUSIONS: In summary, the aggressiveness of N0M0 RCC with RD increased the risk of postoperative recurrence, particularly in the early pathological stage. The short TTR also demonstrated the aggressiveness of RCC with RD.