Loss of Heterozygosity Analysis at Different Chromosome Regions in Wilms Tumor Confirms 1p Allelic Loss as a Marker of Worse Prognosis: A Study from the Italian Association of Pediatric Hematology and Oncology

Abstract

The specific aims of the AIEOP-TW-2003 protocol included prospectively investigating a possible association of tumor loss of heterozygosity with outcomes in children treated for Wilms tumor. We analyzed 125 unilateral favorable histology Wilms tumors registered between 2003 and 2008 in the Italian cooperative protocol for microsatellite markers mapped to chromosomes 1p, 7p, 11q, 16q and 22q. The 3-year disease-free survival and overall survival probabilities were 0.87 (95% CI 0.81-0.93) and 0.98 (95% CI 0.96-1.0), respectively. Loss of heterozygosity at 1p was significantly associated with a worse disease-free survival (probability 0.67 for patients with and 0.92 for those without 1p loss of heterozygosity, p = 0.0009), as confirmed also by multivariate analysis adjusting for tumor stage and patient age at diagnosis. There was no difference in disease-free survival probability among children with loss of heterozygosity in the other chromosomal regions tested. The worse outlook for children older than 2 years at diagnosis did not seem to be influenced by the loss of heterozygosity patterns considered. Chromosome 1p loss of heterozygosity seems to be a risk factor for nonanaplastic Wilms tumor, possibly regardless of other clinical factors. Our findings were uninformative regarding loss of heterozygosity in the other chromosomal regions tested.