MP59-08 POPULATION-BASED COMPARISON OF CANCER SPECIFIC MORTALITY AFTER LOCAL TUMOR ABLATION OR NON-ACTIVE TREATMENT FOR T1A KIDNEY CANCER: A COMPETING RISK ANALYSIS

MP59-08 POPULATION-BASED COMPARISON OF CANCER SPECIFIC MORTALITY AFTER LOCAL TUMOR ABLATION OR NON-ACTIVE TREATMENT FOR T1A KIDNEY CANCER: A COMPETING RISK ANALYSIS

THE JOURNAL OF UROLOGYâ e732 MP59-07 DEFINING THE MALIGNANT POTENTIAL OF ONCOCYTIC RENAL NEOPLASMS Chandra K. Flack*, Adam C. Calaway, Dibson D. Gon...

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THE JOURNAL OF UROLOGYâ

e732

MP59-07 DEFINING THE MALIGNANT POTENTIAL OF ONCOCYTIC RENAL NEOPLASMS Chandra K. Flack*, Adam C. Calaway, Dibson D. Gondim, Muhammad T. Idrees, Ronald S. Boris, Indianapolis, IN INTRODUCTION AND OBJECTIVES: Oncocytomas are benign renal tumors with minimal malignant potential. However, the natural history of indeterminate tumors with oncocytic features such as “oncocytic neoplasm” and “renal cell carcinoma unclassified with oncocytic features” (RCC unclassified) is less clearly understood. Our aim was to compare the oncologic outcomes in oncocytic tumors to those seen in pure oncocytoma to determine their aggressive potential. METHODS: Pathology reports for all partial and radical nephrectomies performed at our institution from 1999 through 2014 were reviewed. Reports with the term oncocytoma, “oncocytic neoplasm,” “oncocytosis,” and “renal cell carcinoma unclassified with oncocytic features” were included in the study. Concurrent renal neoplasms of other histologic subtype (clear cell, papillary, urothelial) and tumors secondary to known hereditary syndrome were excluded. Descriptive statistics were used to compare patients with oncocytic variant tumors to those with pure oncocytoma. RESULTS: Ninety-five patients were included in the study (70 oncocytoma, 6 oncocytic neoplasm, and 19 RCC unclassified). Median overall follow-up time was 31 months (IQR 7 e 69). Follow-up time per cohort was 34 months (IQR 6 e 71) for oncocytoma, 40 (IQR 15 e 77) for oncocytic neoplasms, and 16.5 (IQR 6 e 38) for RCC unclassified. Demographic characteristics (age, sex, race) were similar between the three groups. The majority of tumors in all groups were discovered incidentally. Mean (SD in cm) tumor size was 3.8 cm (2.4) in pure oncocytomas, 2.3 cm (0.9) in oncocytic neoplasms, and 4.5 cm (3.4) in RCC unclassified tumors (p ¼ 0.232). Eight patients had cancer at the resection margin, and all were pure oncocytoma (p ¼ 0.327). In comparing oncologic outcomes, there were no significant differences between the groups. No patients experienced local recurrence or metastasis. One patient with oncocytoma (1%) and 2 patients with RCC unclassified (11%) died during follow-up (p ¼ 0.168). No deaths were related to their renal tumors. CONCLUSIONS: Although representing a small cohort, the data here provide evidence that variant tumors with oncocytic features behave more like oncocytoma than renal cell carcinoma. Surgery appears to be curative and should steer urologists towards a less aggressive post-operative surveillance pathway whenever possible. Source of Funding: none

MP59-08 POPULATION-BASED COMPARISON OF CANCER SPECIFIC MORTALITY AFTER LOCAL TUMOR ABLATION OR NON-ACTIVE TREATMENT FOR T1A KIDNEY CANCER: A COMPETING RISK ANALYSIS Vincent Trudeau*, Alessandro Larcher, Malek Meskawi, Roger Valdivieso, Katharina Boehm, Zhe Tian, Montreal, Canada;  Buffi, Giovanni Lughezzani, Giorgio Guazzoni, Nicola Fossati, Nicolo Milan, Italy; Pierre Karakiewicz, Maxine Sun, Montreal, Canada INTRODUCTION AND OBJECTIVES: The management of non-surgical candidates diagnosed with kidney cancer includes local tumor ablation [LTA] and absence of local treatment [ALT]. However, data regarding cancer-specific mortality [CSM] after LTA or ALT are lacking. Our hypothesis stated that LTA might result in a lower cancer specific mortality relative to [ALT] after adjustment for competing othercause mortality [OCM]. METHODS: A Surveillance Epidemiology and End ResultsMedicare-linked retrospective cohort of 1860 T1a N0 M0 kidney cancer patients who underwent LTA or ALT between 2000 and 2009

Vol. 193, No. 4S, Supplement, Monday, May 18, 2015

was abstracted. ALT was defined as absence of either LTA or any other surgical treatment during the first 6 months after diagnosis. The outcome of the study was CSM defined as death due to kidney cancer. Analyses consisted of propensity-score matching to reduce potential measured differences between LTA and ALT patients. Subsequently, regression models [MVA] adjusted for competing risk of OCM, patient (age) and cancer characteristics (tumor size, histology and grade) were fitted to address the impact of LTA vs. ALT on CSM. RESULTS: Median follow-up was 30 (IQR 14-52) months among survivors. Fewer patients (30%; n¼553) were treated with LTA, while most (70%; n¼1307) received ALT. With respect to ALT patients, individuals treated with LTA were younger (77 vs. 78; p<0.001), more frequently white (84 vs. 78%; p¼0.005), more frequently married (59 vs. 52%; p¼0.02) and more frequently of high socio-economic status (54 vs. 45% p¼0.001). In patients treated with LTA, surgical approach was open, laparoscopic and percutaneous in 6, 52 and 42% of the cohort, respectively. Following a 1:1 ratio propensity score matching for all the covariates, 553 LTA and 553 ALT patients remained. All subsequent analyses were based on the post-propensity score matched cohort. In patients treated with LTA, the 5-years CSM and OCM rates were 3.7 and 22%, respectively. In patients treated with ALT the 5-years CSM and OCM rates were 11 and 37%, respectively. After adjustment for patient and cancer characteristics and for competing risk of OCM, LTA was associated with lower risk of CSM (HR 0.52; CI 0.27-0.98; p¼0.045). Conversely, age (HR 1.04; CI 1-1.08; p¼0.049), and tumor size (HR 1.04; CI 1-1.08; p¼0.03) were associated with higher risk of CSM. CONCLUSIONS: OCM represents the leading cause of death in non-surgical candidates diagnosed with T1a kidney cancer. After adjustment for competing OCM, and for patient and cancer characteristics, LTA results in lower CSM compared to ALT. Source of Funding: None.

MP59-09 IS IT SAFE TO CONTINUE ASPIRIN DURING LAPAROSCOPIC PARTIAL NEPHRECTOMY? Michael Siev*, Paras Shah, David Leavitt, Simpa Salami, New Hyde Park, NY; Vinoth Birabaharan, Hempstead, NY; Mathew Fakhoury, Old Westbury, NY; Manaf Alom, Jessica Kreshover, Lee Richstone, Manish Vira, Louis Kavoussi, New Hyde Park, NY INTRODUCTION AND OBJECTIVES: The surgical population is aging, and patients are increasingly on antiplatelet therapy for secondary prevention of cardiac and thromboembolic events. Traditionally, antiplatelet therapy is discontinued one week prior to laparoscopic partial nephrectomy (LPN) for fear of increased perioperative hemorrhage and complications. However, this practice is not evidence-based, while there is level one evidence showing a decrease in acute coronary events when aspirin is continued perioperatively. We are aware of no reports evaluating LPN in patients continuing aspirin. To this end, we sought to review our LPN experience and to compare outcomes and complications in patients continuing aspirin therapy to those stopping it perioperatively. METHODS: An IRB-approved retrospective review was performed of 430 consecutive LPN cases done between January 2012 and October 2014. All patients on chronic aspirin therapy were identified and separated into two groups. The on-therapy group consisted of patients continuing aspirin throughout the perioperative period. The off-therapy group had aspirin therapy held aspirin temporarily in the perioperative period. Surgical outcomes and complications were compared between groups using the Fisher’s Exact Test for categorical variables and the Kruskal-Wallis Test for continuous variables. RESULTS: Of 430 patients, 112 (26%) were on chronic aspirin therapy. Of those, 19 (17%) continued aspirin perioperatively while the remaining 93 (87%) held aspirin an average of 11.4 days