Treatment for neuroblastoma in children varies significantly based on the risk for relapse classification of the disease. It is estimated that as many as 50-60% of children with high-risk neuroblastoma will eventually suffer a relapse. In children with intermediate- or low-risk neuroblastoma, relapses occur in only 5-15% of cases. If neuroblastoma is going to relapse at all, it usually does so within the first two years after the end of treatment. The likelihood of relapse continues to decline as more and more time passes after treatment is complete. Relapses occurring more than five years after the completion of therapy are rare. Treatment varies depending on the risk of relapse.
Patients with disease classified as low risk have tumors that:
- Are localized to one area
- Can be mostly or completely removed by a surgeon
- Have features which indicate that the tumor is unlikely to spread or come back
In certain circumstances, very young infants may be observed closely for signs of tumor progression without treatment. Sometimes their tumors spontaneously regress or go away and the potential risks of surgery to remove the tumor are not needed.
Your doctor will order blood, urine, and imaging tests at scheduled times to follow the disease. If a low-risk tumor recurs or begins to grow, your doctor may recommend treatment with surgery and/or chemotherapy.
Patients with disease classified as intermediate risk of relapse have tumors that:
- Are not easy to remove completely with surgery
- Have mixed tumor cell characteristics
- May create symptoms related to the tumor compressing other organs
In these cases, moderately intensive chemotherapy is given initially to shrink the tumor and make it easier for the surgeon to remove. Chemotherapy drugs known to work in neuroblastoma will be combined and given in 3 week cycles. Some patients are treated with chemotherapy alone and others require chemotherapy and surgery. Radiation treatment is generally not used for intermediate-risk disease.
After every few cycles of chemotherapy, the healthcare team will perform appropriate radiology examinations and tests of the bone marrow, blood and urine to determine how your child’s tumor is responding to therapy. Your healthcare team will determine the next steps based on the results of these evaluations. The number of chemotherapy cycles will be determined by how the tumor shrinks in response to therapy. When the treatment is completed, your doctor will plan periodic evaluations (which may include CT/MRI and MIBG scans, as well as urine, blood and bone marrow tests) to look for any signs of disease recurrence.
Patients with disease classified as high risk for relapse require strong treatment combining chemotherapy, surgery, stem cell transplant, radiation therapy and immunotherapy. A patient is considered to have high-risk neuroblastoma either because of aggressive characteristics of the tumor cells or the presence of disease in multiple places. Because the outcome for high-risk disease is significantly poorer than for low- and intermediate-risk disease, there are questions regarding the best treatment choices. It is most important that children with high-risk disease are:
- Properly diagnosed by experienced neuroblastoma experts
- Treated at a hospital with experience in treating and monitoring the disease
The majority of high-risk treatment protocols use some combination of the following procedures:
- Induction Chemotherapy: Four to six courses of combined drug chemotherapy is given first to reduce the size of the primary and any metastatic tumor (cancer cells that have spread to other parts of the body). The particular medications and doses vary.
- Surgery to remove as much tumor as possible following the induction chemotherapy.
- Consolidation Therapy involves stem cell transplant. Standard treatment of high-risk neuroblastoma includes the use of very high doses of chemotherapy followed by an autologous (self-donating) hematopoietic (blood cells) stem cell infusion. This a multi-stage process that involves:
- Collecting stem cells from the patient that will be stored for later use. This usually occurs during the induction part of therapy
- Administering very high doses of chemotherapy to eliminate any remaining tumor cells
- Infusing collected stem cells to the patient to restore the bone marrow that has been destroyed by the chemotherapy/radiation
- In some cases the process may be repeated with a different combination of very high dose chemotherapy drugs and a second stem cell transplant. Most doctors agree that using autologous (from the patient) peripheral blood stem cells is preferable to using either autologous bone marrow or allogeneic (from a matched donor) bone marrow in the transplant process. Research has shown that the body more rapidly
“engrafts,” or goes to work restoring the immune system when peripheral blood stem cells are used. In addition, there is less risk of tumor cell contamination. However, in cases where the patients’ own stem cells cannot be harvested from their blood, bone marrow may be used.
- Radiation is given to the primary tumor site. Even if the tumor was completely removed, it is possible that a microscopic amount of tumor remained. Your doctor may also recommend radiation to sites of metastatic disease that have not responded to other therapies.
- Maintenance Therapy (occurring after consolidation): because many high-risk patients experience relapse, doctors give additional medicines or treatments aimed at eliminating or altering small amounts of disease which may still be present after consolidation therapy. These treatments work differently than typical chemotherapy by either causing the tumor cells to mature or by stimulating the body’s immune system to fight cancer. The following therapies are currently being used in this phase of treatment:
- 13-cis-retinoic acid (isotretinoin): Researchers have found that oral retinoic acid causes tumor cells to transform from cancerous, rapidly-dividing immature cells, to mature nerve cells (a process called differentiation).
- Monoclonal antibody therapy (mAb): mAbs alone can attach to the cancer cells and kill them, or be combined with other medicines to directly attack and kill the cancer cells. The antibody being used in the treatment of patients with high-risk neuroblastoma is directed against GD-2, a marker found on the surface of neuroblastoma cells. Unituxin, a treatment for high-risk neuroblastoma, was recently approved by the FDA, is an mAb directed against GD-2.
- Cytokines: Substances that can improve the body’s natural immune response to infection and cancer.
- Colony-stimulating factors: substances that stimulate the production of blood cells to kill cancer cells.
Following completion of maintenance therapy, children with high-risk neuroblastoma are monitored carefully to look for any signs of disease recurrence. Children are also followed in the long term to help manage side effects of treatment that may emerge years later.
About 2-4% of children who develop neuroblastoma also have symptoms of a rare neurological condition called OMA. Children with OMA develop symptoms that include walking and balance problems (ataxia), uncontrollable eye movements (opsoclonus), and body jerking, especially of the feet and legs (myoclonus). The cause of OMA is not completely understood, but it occurs when the auto-antibodies (disease-fighting proteins) that attack the cancer for some reason begin attacking the brain and central nervous system. OMA is usually associated with a less aggressive form of neuroblastoma.
Children with OMA/neuroblastoma must receive coordinated treatment. They usually fall in the low-risk category, so in addition to standard low-risk treatment they may receive:
- Treatment with steroids (either ACTH or prednisone)
- Intravenous gammaglobulin
- Chemotherapy: Studies suggest that chemotherapy may decrease the amount and severity of long-term neurologic problems. Some physicians recommend only low-doses of a single chemotherapy drug, cyclophosphamide.
- If patients do not respond to steroids, gammaglobulin, or chemotherapy, other agents such as rituximab are used