Thesis (M.Sc.) - Cairo University - National Cancer Institute - Department of Pediatrics - Onocology

Background: Wilms tumor (WT) represents 6.5 % of childhood cancers accounting for 87% of pediatric renal tumors. According to the fifth National Wilms Tumor Study (NWTS-5), tumor-specific loss of heterozygosity (LOH) for chromosomes 1p and 16q identifies a subset of WT patients with favorable histology (FH) but have a significantly increased risk of relapse and death. Purpose: The aim of this study was to find out survival outcome of FH-WT patients , and the frequency of 1p and 16q LOH and its impact on their outcome .Methods: data of FH-WT patients presented to the Pediatric Oncology Department National Cancer Institute, Egypt (NCI) during the period from January 2005 to December 2010 was retrospectively analyzed. Clinical and demographic data were reviewed and paraffin blocks were tested for 1p and 16q LOH using polymorphic loci that span the minimal regions of LOH at this area as described in earlier studies. Results: study included 100 patients with a median age of 5 years (8 months-15 years) and male to female ratio; 0.75:1. 39/100 patients showed LOH at 1p (n=14), 16q (n=13), or both (n=12). LOH was most frequently encountered in patients above 10 years of age (4/5), advanced stages disease (80% of stage V and 50% of each stage IV and III patients had LOH). All patients with progressive disease during chemotherapy (n=5) were positive for LOH. The 3 years OS and EFS were significantly lower in patients with double LOH (56%&50%) followed by 16 q (59%&55%) in comparison to 1p (93% each) and negative LOH cases 98% each respectively, p=0.001

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