PATHOLOGICAL CHARACTERISTICS AND PROGNOSTIC IMPACT OF PERITUMORAL CAPSULE PENETRATION IN CLEAR CELL RENAL CELL CARCINOMA AFTER MINIMAL PARTIAL NEPHRECTOMY

Aim: To evaluate the pathological characteristics of peritumoral capsule and the prognostic impact of capsule penetration on tumor recurrence in patients treated by nephron-sparing surgery (NSS) for clear cell RCC. Patients and Methods: Between January 2005 and December 2007, 115 consecutive patients with single sporadic clear cell RCC had NSS. Peritumoral capsule status was carefully analyzed by two dedicated uropathologists. The degree and the side of capsule penetration, if present, were evaluated. Results: According to the peritumoral capsule status, in 68 (59.1%) the capsule was intact and free from neoplastic penetration (PC–), while in 47 (40.2%) there were signs of invasion within its layers. Overall, 29.6% had capsular penetration on the parenchymal side (PCK), whereas, 11.3% had peritumoral capsule invasion on the perirenal fat tissue side (PCF). None of the patients had positive surgical margins detected at the pathological examination. Mean (median, range) follow-up was 48 months (46, 25-69). The 5-year cancer-specific and progression-free survival were 91.7% and 89.5%, respectively. The 5-year progression-free survival for tumors PC–, PCK and PCF was 97%, 96.2% and 48.5%, respectively (p<0.0001; PC- vs. PCF p<0.0001; PCK vs. PCF p=0.0002). The multivariate Cox model showed PCF to be the sole significant independent predictor of progressionfree survival. Conclusion: PCF is a significant and independent predictor of worse outcome. Patients with clear cell RCC with intact peritumoral capsule, as well as those with PCK, had an excellent prognosis and these pathological features could possibly add to prognostic nomograms if proved statistically significant in larger series with longer follow-up.