1312 CHANGES IN RENAL FUNCTION AFTER RENAL SURGERY AND THE ANALYSIS OF FACTORS AFFECTING THE DEVELOPMENT OF CHRONIC RENAL INSUFFICIENCY; MULTICENTER STUDY

of the PC away from normal renal parenchyma) is classically used for familial Renal Cell Carcinoma (RCC) but has not been widely adopted for sporadic RCC. We investigate whether tumor histology predicts the presence, thickness, and extension of tumor through the PC, potentially identifying tumors best suited for a TE nephron-sparing approach. METHODS: Twenty-five consecutive total or partial nephrectomies for pT1 clear cell, papillary, chromophobe, and oncocytoma were included (N 100 total tumors). Specimens were reviewed for numerous pathological features including stage, grade, lympho-vascular invasion, as well as characteristics of PC such as capsular presence/ absence, mean thickness, continuity, and tumor capsule invasion (TCI). PC parameters (thinnest, thickest and mean) were calculated from multiple measurements using an ocular micrometer, rounded to the nearest tenth of a millimeter. RESULTS: Tumor sizes in each group were similar. PC was complete in: papillary (n 21, 84%), clear cell (n 19, 76%), chromophobe (n 7, 28%), and oncocytoma (n 1, 4%); present but incomplete in oncocytoma (n 14, 56%), chromophobe (n 11, 44%), clear cell (n 6, 24%), and papillary (n 2, 8%); and absent in oncocytoma (n 10, 40%), chromophobe (n 7, 28%), papillary(n 2, 8%), and clear cell (0%). TCI was seen in 30% of papillary and only 8% of clear cell (p-value 0.006) PC. When present, mean thickness of the PC was significantly thicker for clear cell (0.8mm) when compared to the other tumors (papillary and chromophobe 0.6mm and oncocytoma 0.3mm). Multivariate logistic regression demonstrated only tumor type to be significantly associated with TCI (p-value 0.046, OR 10.3 (95%CI)). CONCLUSIONS: In pT1 renal tumors, PC appears predictable based on tumor histology. The PC is likely to be absent or incomplete in renal oncocytoma and chromophobe. Papillary RCC demonstrates the highest % of TCI which could predict higher surgical margin rates during TE surgery. Clear cell RCC possesses the thickest, most complete tumor capsule with minimal TCI and may be best suited for TE partial nephrectomy.