PERITUMORAL PSEUDOCAPSULE INVASION DOES NOT AFFECT THE RISK OF LOCAL RECURRENCE AFTER TUMOR ENUCLEATION IN THE TREATMENT OF RENAL CELL CARCINOMA

Introduction: Peritumoral pseudocapsule (PS) invasion after tumor enucleation (TE) in the treatment of renal cell carcinoma (RCC) could potentially affect the risk of local recurrence. The aim of the present study is to prospectively evaluate this hypothesis in a consecutive series of patients having TE for RCC. Methods: TE was done by blunt dissection in 201 consecutive patients using the natural cleavage plane between the tumor and normal parenchyma. Pseudocapsule penetration, surgical margin (SM) status and routine clinical and pathological variables were recorded. Results: Overall, 164 tumors were diagnosed as single sporadic RCCs and thus included in the study. Mean (SD, median, range) tumor greatest dimension was 3.5 (1.7, 3.2, 1.0-12.5) cm. At the pathological examination, the PS was intact and free from invasion on the parenchymal side in 73.2%, while it was penetrated on the parenchymal side in 26.9% of RCCs. In all cases the SM were negative. Even in patients with pseudocapsule penetration and invasion beyond it, neoplastic cells were separated from the surgical margin by a thin layer of normal tissue with signs of lymphoplasmocytic inflammation. The 3-year overall survival was 95.5%. The 3- year cancer-specific and progression-free survival were 100% and 96.6%, respectively. After a mean (range) follow-up of 44 months (25-69), the true local recurrence rate was 0.6%. None of the RCCs with pseudocapsule penetrated on the parenchymal side recurred locally. Conclusion: TE is oncologically safe. Peritumoral pseudocapsule invasion does not influence the risk of local recurrence when TE is adopted for the treatment of RCC.