1. Visceral Adiposity at Diagnosis Correlates with Tumor Size and Metastatic Progression in Clear Cell Renal Carcinoma A Shuster, MD (1), M Patlas, MD (1), S.A Hiltz, MD (2), A Kapoor, MD (2), J.H Pinthus, MD, PhD (3) Introduction  Renal cell carcinoma (RCC), the most common type of kidney cancer in adults, accounts for 85%-90% of all kidney tumors, and for approximately 3% of adult malignancies. RCC ranks as the 9th leading cause of cancer mortality in western industrialized countries.  Obesity is an established risk factor for renal cell carcinoma (RCC).  The visceral adipose tissue (VAT) is an endocrine active fat compartment and an accurate predictor of obesity related morbidity. Objectives  To analyze the effect of visceral adiposity in RCC patients at presentation on their disease characteristics and progression. Materials and Methods:  Prospective data base of 140 patients with clear cell RCC (97 males and 43 females) have been collected over a 3-year period.  All patients had computed tomography (CT) scan at diagnosis available for analysis and underwent either radical or partial nephrectomy.  Visceral, subcutaneous and total adipose tissue volumes have been obtained from 3 representative axial slices at 3 fixed levels (L2 vertebral body, umbilicus and anterior superior iliac spine), using software: ClearImage Demo Version 2.1.12 (Inlite Research, Inc. 2007). Tissue of fat density was defined within -250 to -30 Hounsfield Units. A ratio of visceral adipose tissue to total adipose tissue (%VAT) was then calculated across 3 slices. Subcutaneous Fat (highlighted) Visceral Fat (highlighted) Original axial slice. Right- sided RCC is seen (arrows) Total fat is extracted Results  Mean age, tumor size and %VAT were 59.5, 5.54cm and 41.4% respectively.  Male patients had significantly higher mean %VAT then female (46.1 and 30.7, p<0.001)- Fig 1, and larger tumor size (5.93cm vs. 4.66cm p=0.03), but almost the same percentage of metastasic cases (26% and 28% respectively).  %VAT was also appreciably higher in metastatic as compared to non-metastatic cases (36% vs. 28.63% p=0.005) but only in female patients. Fig 2 Conclusion  Greater percentage of VAT correlated with clear cell RCC larger than 3cm in all patients.  Greater percentage of VAT correlated metastatic progression in female patients. Department of Diagnostic Imaging, Hamilton General Hospital (1), and Departments of Surgery-Urology, St. Joseph’s Healthcare Hamilton (2), and Juravinski Cancer Centre (3), Faculty of Health Sciences, McMaster University  Patients with tumors larger than 3 cm had significantly higher %VAT than those with smaller tumors – Fig 3 (43.6% vs.35.1%, p= 0.0001). Correlation between VAT% and Tumor Size 10 20 30 40 50 60 70 0123456789101112131415161718 Size (cm) VAT% 43.6 35.143.2 38.7 43.4 39.5 0 5 10 15 20 25 30 35 40 45 VAT% 123 Tumor Tumor Tumor VAT% distribution in RCC patients due to tumor size 30.7 46.1 0 10 20 30 40 50 VAT% Distribution of VAT% in Genders Females Males *p= 0.0001 36.07 28.63 10 15 20 25 30 35 40 VAT% Distribution of VAT% in Females with and without Mets Without Mets With Mets * p=0.005 Fig 1 Fig 2 * Fig 1 * Fig 3 Note: more linear correlation exists between %VAT and tumor size< 4cm