In North America, the Children's Oncology Group (COG) investigated a risk-based neuroblastoma treatment plan that assigned all patients to a low-, intermediate-, or high-risk group based on age, International Neuroblastoma Staging System (INSS) stage, and tumor biology (i.e., MYCN gene amplification, International Neuroblastoma Pathology Classification [INPC] system, and DNA ploidy). The intermediate-risk group received limited chemotherapy, additional surgery in some instances, and avoided radiation therapy. This study involved an overall reduction in treatment compared to prior treatment plans. Event-free survival (EFS) and overall survival (OS) rates were 88% and 96%, respectively. There was no unexpected toxicity. These studies (COG-P9641 and COG-A3961) have established a new standard of care for children in North America with neuroblastoma. (Risk groups are defined in Table 1 in the Stage Information section of this summary.)
Chemotherapy is given for four to eight cycles (12 to 24 weeks) and consists of moderate doses of carboplatin, cyclophosphamide, doxorubicin, and etoposide. The cumulative dose of each agent is kept low to minimize permanent injury from the chemotherapy regimen. Radiation therapy is reserved for patients with symptomatic life-threatening or organ-threatening tumor that does not respond rapidly enough to chemotherapy and/or surgery.
There is considerable variation in outcome, and, therefore, in treatment for children with stage 3 disease (tumor involving both sides of the midline by virtue of either invasion into normal tissues or lymph node metastasis). Infants aged 1 year and younger have a greater than 80% cure rate while older children have a cure rate of 50% to 70% with current, relatively intensive therapy.[2,3,4,5] In one study, those with favorable compared with unfavorable biological features (i.e., INPC and MYCN gene amplification) had EFS rates of almost 100% and about 50%, respectively.[6,7,8] In cases of abdominal neuroblastoma thought to involve the kidney, nephrectomy should not be undertaken before a trial of chemotherapy has been given.
Whether initial chemotherapy is indicated for all intermediate-risk infants with localized neuroblastoma is controversial. A German prospective clinical trial enrolled 340 infants aged 1 year or younger whose tumors were stage 1, 2, or 3, histologically verified, and lacked amplification of MYCN. Chemotherapy was given at diagnosis to 57 infants with organs threatened by tumor. The tumor was completely resected or nearly so in 190 infants who underwent low-risk surgery. A total of 93 infants whose tumors were not resectable without high-risk surgery due to age or organ involvement were observed without chemotherapy. Further surgery was avoided in 33 infants and chemotherapy was avoided in 72 infants. Some degree of spontaneous tumor regression occurred in nearly half the infants. Overall survival of the 93 infants was 99%.