MSH2 MUTATIONS AND BLADDER CANCER RISK: FAMILY MEMBERS OF HEREDITARY NONPOLYPOSIS COLORECTAL CANCER PATIENTS WITH MSH2 MUTATIONS ARE AT INCREASED RISK NOT ONLY FOR UPPER TRACT TRANSITIONAL CELL CARCINOMA BUT ALSO BLADDER CANCER

753 MSH2 MUTATIONS AND BLADDER CANCER RISK: FAMILY MEMBERS OF HEREDITARY NONPOLYPOSIS COLORECTAL CANCER PATIENTS WITH MSH2 MUTATIONS ARE AT INCREASED RISK NOT ONLY FOR UPPER TRACT TRANSITIONAL CELL CARCINOMA BUT ALSO BLADDER CANCER Sean Skeldon, K Semotiuk, Steve Gallinger, Neil E Fleshner, Michael A S Jewett, M Cotterchio, Alexandre R Zlotta*. Toronto, ON, Canada. INTRODUCTION AND OBJECTIVE: Several studies have reported abnormal MSH2 immunohistochemical expression in bladder tumours, a mismatch repair gene mutated in hereditary nonpolyposis colorectal cancer (HNPCC) families. A correlation between HNPCC and upper tract transitional cell carcinoma (UTCC) had been previously described, but information about bladder cancer risk in MSH2 mutations within these families has not been conclusive. In this study, the risk of