Which of the following statements regarding neuroblastoma are true?

a. Neuroblastoma is the most common abdominal malignancy of childhood

b. Approximately 80% of neuroblastoma patients are diagnosed prior to age 4 years

c. N-myc oncogene copy number in neuroblastoma tissue is inversely related to survival probability

Neuroblastoma is the most common extracranial solid tumor and the most common abdominal malignancy of childhood. The incidence is approximately 8 to 10 per million children under the age of 15 years. The incidence is uniform throughout the world. This results in approximately 500 new cases reported each year in the United States. The median age at diagnosis is about 2 years and 80% of children are less than four years of age at diagnosis. The N-myc oncogene, whose function and mechanism of action remain the subject of investigation, was empirically shown to be a useful predictor of survival and risk. It was found that patients with increased copies of the N-myc gene had a much worsened prognosis. Currently, most authorities consider a copy number of more than ten to be significant. The trk proto-oncogene is a component of the highaffinity nerve growth factor receptor and is expressed in human neuroblastoma tissue. Trk-A expression is inversely correlated with N-myc amplification and is associated with lower stage at diagnosis and improved prognosis.