Oncological outcomes after partial vs radical nephrectomy in renal cell carcinomas of ≤7 cm with presumed renal sinus fat invasion on preoperative imaging

OBJECTIVES: To compare oncological outcomes of partial nephrectomy (PN) and radical nephrectomy (RN) for renal tumours of ≤7 cm in which preoperative imaging reveals potential renal sinus fat invasion (cT3a), as RN is preferred for these tumours due to concerns about high tumour stage. PATIENTS AND METHODS: Among 1137 nephrectomies performed for renal tumours of ≤7 cm from January 2005 to August 2012, 401 solitary cT3a renal cell carcinomas (RCCs) without metastases were analysed. Classification as cT3a included only renal sinus fat invasion, as there were no tumours with suspected perinephric fat invasion. Multivariate models were used to evaluate predictors of recurrence-free survival (RFS) and cancer-specific survival (CSS). RESULTS: There were 34 RCCs (8.5%) with unexpected perinephric fat invasion, but only 77 RCCs (19.2%) were staged as pT3a. During the median follow-up of 43.0 months, recurrence occurred in seven (6.7%) PN cases and 25 (8.4%) RN cases. Six recurred PN cases had positive surgical margins (PSMs). The two cohorts showed equal oncological outcomes for 5-year RFS and CSS. Multivariate analyses showed PSM, pathological T stage, sarcomatoid dedifferentiation, and type of surgery as significant predictors of recurrence. Older age, pathological T stage, and sarcomatoid dedifferentiation were significant predictors of cancer-specific mortality. CONCLUSIONS: Renal tumours of ≤7 cm with presumed renal sinus fat invasion were mostly pT1. PN conferred equivalent oncological outcomes to RN. If clear surgical margins can be obtained, PN should be considered for these tumours, as patients may benefit from renal function preservation.