Pathological characteristics and prognostic effect of peritumoral capsule penetration in renal cell carcinoma after tumor enucleation

Abstract

Objective: To evaluate the pathological characteristics of peritumoral capsule (PC) and the prognostic effect of capsule penetration on tumor recurrence in patients treated with tumor enucleation for clinically intracapsular renal cell carcinomas (RCCs).

Methods and materials: PC status was analyzed in 304 consecutive patients with single intracapsular RCC. Degree and side of capsule penetration if present were evaluated. Mean (median, range) follow-up was 49 months (46, 25-69). Local recurrence rate, progression-free survival (PFS), and cancer-specific survival were the main outcomes. Statistical analyses included the Kaplan-Meier method, log-rank test, and univariate and multivariate Cox regression models.

Results: Overall, 51% of RCCs had intact PC and free from neoplastic invasion (PC-), 34.9% had capsular penetration on the parenchymal side (PCK), and 14.1% had tumor invasion on the perirenal fat tissue side (PCF). None of the patients had positive surgical margins. The 5-year PFS rates for tumors PC-, PCK, and PCF were 97.5%, 96.7%, and 77.1%, respectively (P<0.0001). The multivariate Cox model showed PCF to be the sole significant independent predictor of PFS, whereas patients who had PCK did not present a significant increased risk in developing recurrence.

Conclusions: Tumor enucleation is an oncologically safe nephron-sparing surgery technique. PCF is a significant and independent predictor of tumor recurrence in patients with clinically intracapsular RCCs scheduled for nephron-sparing surgery. PCK does not predict the risk of recurrence.

Keywords: Capsular invasion; Partial nephrectomy; Peritumoral capsule; Prognosis; Renal cell carcinoma; Tumor enucleation.