Molecular basis of clinical heterogeneity in neuroblastoma.

Neuroblastomas are heterogeneous in terms of both their genotype and their clinical behavior. Recent studies suggest that these two features are related, and that the genotype frequently is predictive of response to treatment or the outcome of the patient. The genetic abnormalities that are characteristic of certain neuroblastomas include: (a) loss of heterozygosity (LOH) for the short arm of chromosome 1, including band 1p36; (b) amplification of the N-myc protooncogene; and (c) hyperdiploidy, or near-triploidy, determined either by flow cytometry or by karyotype. Hyperdiploidy is associated with lower stages of the tumor and with a favorable outcome in infants. However, LOH for chromosome 1 (band p36) and N-myc amplification are more common in patients over 1 year of age who have advanced stages of the tumor. Based on analysis of neuroblastomas for these genetic abnormalities, three distinct genetic subsets can be identified. The first is characterized by a hyperdiploid or near-triploid modal karyotype, with few, if any, cytogenetic rearrangements. These patients are generally less than 1 year of age, they have localized tumors, and have a good prognosis. The second genetic subset has a near-diploid karyotype, but with no consistent abnormality identified to date. They are generally older patients with tumors in the more advanced stages that progress slowly and are often fatal. Patients in the third group of genetic abnormalities have a near-diploid or tetraploid karyotype, with deletions or loss of heterozygosity for 1p36, amplification of N-myc, or both. These patients are generally older; they have advanced stage tumors that are rapidly progressive.(ABSTRACT TRUNCATED AT 250 WORDS)