INTERSTITIAL AND LARGE CHROMOSOME 1P DELETION OCCURS IN LOCALIZED ANDDISSEMINATED NEUROBLASTOMAS AND PREDICTS AN UNFAVORABLE OUTCOME

We studied chromosome Ip loss of heterozygosity (1p-LOH) in 53 neurobl astomas (NBs) using 15 (CA)n repeat loci, which covered a region of 90 cM. We also assessed chromosome 1p36 deletion by fluorescence in situ hybridization (FISH) on interphase nuclei. 1p-LOH was found in 19 (36 %, 95% confidence interval (CI) 23-50%) NBs. We detected interstitial and large deletion in both localized and disseminated tumours and in o ne tumour of a patient at stage 4S. Allelic loss was frequently observ ed in 1p36 and 1p32 regions. In patients older than 1 year of age (53 Versus 13%, P < 0.002) we detected significant chromosome 1p deletion and it was associated with MYCN amplification (P = 0.001). Overall sur vival (OS) analysis showed that 1p-LOH is predictive of a poor outcome (odds ratio 16.5, 95% CI 5.4-50.9%); therefore, 1p-LOH should be rega rded as an additional tumour progression marker in neuroblastoma. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.