MP64-04 RETROPERITONEAL PARTIAL NEPHRECTOMY FOR POSTERIOR TUMORS: IS IT BETTER THAN THE TRANSPERITONEAL APPROACH?

Abstract

INTRODUCTION AND OBJECTIVES: Approximately 2.7-10% of patients with renal cell carcinoma (RCC) have lymph node (LN) metastases in the absence of distant metastatic disease. We have previously reported that patients with only nodal metastases who undergo a LND at the time of nephrectomy have durable disease-free survival. We sought to identify clinical predictors of positive lymph nodes in patients with locally advanced RCC. METHODS: IRB approval was obtained to search an institutional nephrectomy database for patients with RCC without distant metastasis who underwent radical or partial nephrectomy with a lymph node dissection (TanyNanyM0). Preoperative variables were collected such as demographic information, local/systemic symptoms, ECOG performance status (PS), laboratory values, clinical T/N stage, as well as radiographic information such as tumors size, presence of necrosis, presence of tumor thrombus, and tumor location. Univariate analysis (UVA) was performed to determine significant covariates between pN1 and pN0 patients. Continuous and categorical variables were compared using the Wilcoxon-rank sum test, and Fischer exact test, respectively. Significant covariates were then used in a multivariate logistic regression model to determine predictors of pathologically positive LNs. A subset analysis was performed between cN0pN1 and cN0pN0 patients to determine predictors of occult LN metastasis. Cancer specific survival stratified by clinical and pathologic nodal status was estimated using the Kaplan Meier Method. RESULTS: Of the 564 patients who met the inclusion criteria, 131 (23%) and 433 (77%) patients were pN1 and pN0, respectively. 60 patients were cN1pN0 and 29 patients were cN0pN1. On UVA, tumor size, clinical T/N stage, ECOG PS, local/systemic symptoms, ASA score, and abnormal Hgb and LDH were statistically significant. On MVA, the statistically significant variables were ECOG PS, cN stage, local symptoms (flank pain, hematuria), and elevated LDH. During the subset analysis, only local symptoms remained statistically significant. CSS between cN0pN0, cN0pN1, and cN1pN1 patients was also statistically significant (p<0.001). CONCLUSIONS: The presence of local symptoms, ECOG PS, cN stage, and elevated LDH were independent predictors of lymph node metastasis. Patients with clinically negative but pathologically positive LNs represent a small subset of RCC patients (7% in this cohort) and remain an elusive group to identify pre-operatively. The incidence of clinically positive but pathologically negative LNs (37%) is not insignificant.