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Neuroblastoma, a tumor of the postganglionic sympathetic nervous system, is the most common extracranial solid tumor of childhood.
No environmental exposures or agents have been associated with an increased risk of neuroblastoma. However, a subset has a genetic predisposition that follows an autosomal dominant pattern of inheritance.
Primary tumors generally arise in the adrenal medulla (50 percent) or elsewhere in the abdomen or pelvis (30 percent). Only 20 percent arise in the chest.
Metastases usually are found in the regional lymph nodes, bone, bone marrow, skin, or liver. Paraneoplastic syndromes characteristic of neuroblastomas are seen in a small percentage of patients.
Tissue biopsy or characterization of cells in the bone marrow diagnoses neuroblastomas. Catecholamine metabolites are elevated in the urine in over 90 percent of cases.
There is an international neuroblastoma staging system for categorizing the extent and resectability of the primary tumor and the presence or absence of metastases.
A number of prognostic variables have been identified that allow better prediction of clinical behavior: MYCN amplification, allelic loss of 1p36, gain of 17q, expression of TrkA, tumor cell ploidy, and tumor pathology.
Histologically, neuroblastic tumors can be immature (neuroblastoma), partially mature (ganglioneuroblastoma), or completely mature (ganglioneuroma). However, other features, such as the presence or absence of Schwannian stroma, mitoses, or karyorrhectic cells, may have more prognostic importance.
Localized, resectable tumors can be cured by surgery alone. Unresectable tumors or metastatic disease in infants require mild to moderately intensive chemotherapy. Metastatic disease in older patients, and regional tumors with unfavorable biological features in any age, require intensive chemotherapy, frequently with bone marrow or stem cell rescue.
Screening of infants for neuroblastoma by measuring urinary catecholamine metabolites has resulted in a doubling of the apparent incidence rate in infants with no decrease in advanced disease in older children.
Future therapeutic approaches may be aimed at the induction of differentiation or programmed cell death through retinoid or neurotrophin receptor pathways. Alternate approaches may focus on the product of the MYCN gene, the 1p36 suppressor gene, other specific genetic changes, or antiangiogenesis.
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Few tumors have engendered as much fascination and frustration for clinical and laboratory investigators as neuroblastoma. This tumor of the postganglionic sympathetic nervous system is the most common solid tumor in childhood. Interestingly, some infants with metastatic disease can experience complete regression of their disease without therapy, and some older patients have complete maturation of their tumor into a benign ganglioneuroma. Unfortunately, the majority of patients have metastatic disease that grows relentlessly despite even the most intensive multimodality therapy. Indeed, despite dramatic improvements in the cure rate for other common pediatric neoplasms, such as acute lymphoblastic leukemia or Wilms tumor, the improvement in the overall survival rate of patients with neuroblastoma has been relatively modest.
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Recent advances in understanding the biology of neuroblastoma, however, have provided considerable insight into the genetic and biochemical mechanisms underlying these seemingly disparate behaviors. Near ...