Neuroblastoma is a type of cancer that originates in immature nerve cells, known as neuroblasts. These cells are part of the sympathetic nervous system, which controls involuntary bodily functions like heart rate and digestion. This cancer primarily affects infants and young children, often before the age of five, making it the most common cancer diagnosed in babies. While it can develop anywhere along the sympathetic nervous system, it most frequently arises in the adrenal glands, located atop the kidneys. When neuroblastoma spreads from its original site to other parts of the body, it is termed metastatic neuroblastoma.
Understanding Metastatic Neuroblastoma
Neuroblastoma can begin in various locations, but the adrenal glands are the most common primary site, accounting for 40% of localized tumors and 60% of widespread cases. The term “metastatic” signifies that cancer cells have detached from the primary tumor and traveled through the bloodstream or lymphatic system to establish new tumors in distant areas of the body.
Neuroblastoma commonly spreads to the bone marrow, bones, liver, and lymph nodes. Metastasis often places the disease into a high-risk category, which requires more intensive treatment strategies. There is a specific stage known as Stage MS, where metastasis is confined to the skin, liver, or bone marrow in children younger than 18 months, which often has a more favorable outlook compared to other metastatic forms.
Identifying Metastatic Neuroblastoma
The signs and symptoms of metastatic neuroblastoma can vary widely depending on where the cancer has spread. Children might experience bone pain or develop a palpable lump in the abdomen, neck, or chest. Unexplained fevers, fatigue, and a swollen abdomen are also common indicators. If the cancer affects the area around the eyes, bruising or swelling, often described as “raccoon eyes,” may be observed.
Diagnosis begins with a physical examination. Blood and urine tests are performed to detect elevated levels of catecholamine metabolites, such as vanillylmandelic acid (VMA) and homovanillic acid (HVA), which are chemicals produced by neuroblastoma cells. Imaging scans, including MRI, CT, MIBG, and PET scans, pinpoint the tumor’s location and assess its spread. A bone marrow aspiration and biopsy, along with a tumor biopsy, are also conducted to confirm the presence of cancer cells and analyze their characteristics. These tools help in staging the disease based on its extent and other factors.
Treatment Approaches for Metastatic Neuroblastoma
Treatment for high-risk metastatic neuroblastoma is multi-modal, involving aggressive therapies. Initial treatment often begins with intensive chemotherapy to shrink the primary tumor and reduce the metastatic burden. This approach aims to make subsequent treatments more effective.
Following initial chemotherapy, surgical resection of the primary tumor is considered if feasible. The goal of surgery is to remove as much visible tumor as possible to improve outcomes. This step is tailored to each patient’s specific tumor characteristics and response to initial treatment.
High-dose chemotherapy with autologous stem cell rescue, also known as a stem cell transplant, is a standard component of therapy. This involves administering very high doses of chemotherapy to eliminate remaining cancer cells. The patient’s own previously collected stem cells are then reintroduced to help the bone marrow recover, allowing for higher chemotherapy doses.
Radiation therapy is frequently used to target the primary tumor site or areas of metastatic disease that persist after other treatments. This localized therapy delivers high-energy rays to destroy cancer cells and prevent recurrence in specific areas. The specific dose and areas treated are carefully planned to maximize effectiveness while minimizing side effects.
Immunotherapy, particularly with anti-GD2 monoclonal antibodies like dinutuximab, has significantly improved outcomes for children with high-risk neuroblastoma. These antibodies work by targeting a specific molecule (GD2) found on neuroblastoma cells, signaling the body’s immune system to attack the cancer. This therapy is often given after other intensive treatments to help prevent relapse. Ongoing clinical trials continue to explore new and emerging therapies, including other targeted drugs and combinations, to further enhance treatment effectiveness and reduce long-term side effects for children with this challenging disease.
Outlook and Long-Term Care
While metastatic neuroblastoma presents significant challenges, advancements in treatment have led to improved outcomes for many children. Survival rates have shown considerable improvement over recent decades, though they can vary greatly depending on factors such as the child’s age at diagnosis, specific tumor biology, and how well the cancer responds to treatment.
Long-term follow-up care is an ongoing and important part of managing neuroblastoma survivors. This care involves regular monitoring for any signs of cancer recurrence, which can happen years after initial treatment. Additionally, survivors are closely monitored for potential late effects of the intensive treatments received. These late effects can include cardiac issues, kidney problems, hearing loss, and in some cases, the development of secondary cancers. Providing comprehensive support and managing these potential long-term implications are important for maintaining the quality of life for survivors.