PATHOLOGICAL CHARACTERISTICS AND SURVIVAL FOLLOWING PARTIAL NEPHRECTOMY IN PATIENTS WITH SMALL RENAL MASSES SUITABLE FOR MINIMALLY INVASIVE THERAPIES

Introduction: The number of incidentally detected small renal masses is increasing due to the extensive use of imaging techniques. Similarly, elective nephronsparing surgery (NSS) is more and more often used Material and methods: We collected the data of 572 patients undergoing NSS from 1995 to 2007 for <3-cm renal lesion at 16 Italian academic institutions contributing to the SATURN (Surveillance And Treatment Update Renal Neoplasms) project. The Kaplan-Meier method was used to calculate survival functions, and differences were assessed with the log-rank statistic. Univariable and multivariable Cox regression models addressed cancerspecific mortality. Results: Mean age at surgery was 60.3 years. NSS was performed under elective indication in 524 cases (91,6%), whereas it was imperative in 48 cases (8,4%). Pathological evaluation demonstrated clear cell renal cell carcinoma (RCC) in 77.8% of the cases, papillary RCC in 15%, chromophobe RCC in 6.6%, unclassified RCC in 0.5%. Sarcomatoid dedifferentiation was present in 1% of the evaluated cases. Fuhrman grade was 1 in 28.5%, 2 in 58.4%, 3 in 11.9%, and 4 in 0.5%. At a median follow-up duration of 44 mo, 2.3% and 6.1% of the patients experienced cancer-related and non-cancer related deaths, respectively. Overall 10-yr cancer-specific survival (CSS) estimate was 96.9%. On univariable analyses, age, pT stage, Fuhrman grade, and sarcomatoid dedifferentiation were significantly associated with CSS. On multivariable analyses, once excluded sarcomatoid dedifferentiation for colinearity with grade, all the other variables were independent predictor of CSS (all p values < 0.05). Conclusion: NSS allows excellent CSS in patients with small renal masses, which are the benchmark for the evaluation of minimally-invasive therapies. Patients age, pathological T stage, and grade were all independent predictors of CSS.