The prognosis can be reworded as an estimate of the curability. The expressions "favorable prognosis" and "poor prognosis" are often used, and a favorable prognosis means that the disease is highly curable.
It is possible to predict whether or not the prognosis is favorable before the start of treatment. Factors (given conditions) that can predict the subsequent clinical outcome are called prognostic factors. Previous studies have identified prognostic factors for each type of cancer.
Important prognostic factors of neuroblastoma are clinical stage, age at onset, histological type/appearance of tumor cells, number of chromosomes in the tumor cells, and N-myc gene copy number in the tumor cells. Based on these factors, the risk group is determined (see the section of risk groups).
Risk groups of neuroblastoma are the low risk group, intermediate risk group, and high risk group, and an appropriate treatment option is chosen according to the risk.
Low-risk neuroblastomas are most curable, and approximately 90% of patients with this disease may be cured with surgery alone. Relatively mild chemotherapy is required for the remaining 10% of patients. Overall, 90% to 100% of patients survive for a long time. Therefore, one of the challenges is to reduce complications associated with treatment as far as possible.
Intermediate-risk neuroblastomas require more intensive chemotherapy than low-risk neuroblastomas do. If there are metastatic sites, they are radiated. Overall, 70% to 90% of patients survive for a long time with these treatments. Since complications associated with treatment cannot be overlooked, the challenge is to reduce complications and improve the treatment outcome.
High-risk neuroblastomas are the hardest to cure. The main treatment option is chemotherapy. Generally, extremely high-dose chemotherapy consisting of the most intensive chemotherapy and hematopoietic stem cell transplantation, and subsequent radiation therapy are administered. Surgery is complementary. Overall, long-term survival rate is approximately 30% despite the intensive treatment. The greatest challenge is to improve the survival rate.