Molecular and genetic bases of neuroblastoma.

Neuroblastoma, which is derived from the sympathetic nervous system, is the second most common pediatric solid malignant tumor. This pediatric tumor has a heterogeneous course, ranging from spontaneous regression to inexorable progression and death, depending on the biological features of the tumor. Identification of risk groups on the basis of clinical and molecular prognostic variables has allowed tailor-made therapy to improve outcomes and minimize the risk of deleterious consequences of therapy. In Japan, current therapeutic stratification of patients with neuroblastoma is based on risk assessment according to combinations of age, tumor stage, MYCN status, DNA ploidy status, and histopathology; however, unfavorable neuroblastoma is still one of the most difficult tumors to cure, with only 40 % long-term survival despite intensive multimodal therapy. Further refined therapeutic stratification based on newly identified prognostic factors will be required to improve the outcome of patients with unfavorable neuroblastoma and reduce the side effects of therapies for patients with favorable neuroblastoma. In the present review, we describe recent topics on the molecular and genetic bases of neuroblastoma; we hope this review will be helpful for understanding the mechanism of neuroblastoma tumorigenesis and aggressiveness and for developing a new therapeutic stratification and new protocols for neuroblastoma treatments.