More than 900 samples of neuroblastoma were screened for loss of chromosomal material at two loci, 1p36 and 11q23. These abnormalities were associated with high-risk features of neuroblastoma or a poor clinical outcome. In samples of neuroblastoma that were screened for loss of chromosomal material at two loci, abnormalities were associated with high-risk features of neuroblastoma or a poor clinical outcome. Neuroblastoma is a cancer of early childhood in which genomic changes in the tumor correlate with its behavior and outcome in patients. 1 , 2 The algorithm devised by the Children's Oncology Group for risk assessment in cases of neuroblastoma has been successful in distinguishing patients with aggressive disease from those with a high likelihood of cure after surgery or even observation alone. The algorithm stratifies patients into three subgroups with expected low, intermediate, and high risks of death from neuroblastoma. This system involves the use of the clinical factors of age at diagnosis, tumor stage, and the results of the Shimada . . .