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Pediatric brain tumours are the most common solid tumors of childhood, and comprise up to 20% of all childhood cancers. In this article, the three most common pediatric brain tumors are discussed including astrocytomas, medulloblastomas and ependymomas.

Pediatric brain tumors are the most common solid tumors of childhood, and comprise up to 20% of all childhood cancers. There are many different types of brain tumors with varying incidence and severities. Brain tumors can be hard to diagnose as the symptoms and signs of brain tumors in children are not specific and therefore, can be attributed to other more common disorders [1]. You will find more information about rare brain tumors in children here. In this article however, the three most common types of pediatric brain tumors are discussed which include: 

  • astrocytomas,
  • medulloblastomas and
  • ependymomas.

Astrocytomas

Astrocytoma is the most common pediatric brain tumor, and comprises about 50% of all central nervous system cancers. These are generally slow-growing tumors that develop in children between the ages of five and eight, though they have been found in older children as well. Different subgroups of astrocytomas can vary from each other in many different aspects including the location of tumor within the CNS, the tendency towards becoming malignant, the length of time the tumor takes to grow and the size of the tumor.

Fortunately, most astrocytomas are low-grade and therefore, are more likely to be benign [2].

The incidence of astrocytoma in children less than 15 years of age is 14 cases per million children [3].

For low-grade astrocytomas, the survival rate is very good, reaching as much as 95-100% upon the removal of the tumor. If the tumor is located in a sensitive area of the brain, then the surgeon may only be able to remove some of the tumor, which lowers the survival rate, but can still be as high at 60-80%.

In high grade astrocytomas, the survival is much lower at approximately 10-30% depending on the location of the tumor. Furthermore, patients with high grade astrocytomas can develop seizures which can enhance the chance of mortality.

Generally, patients with astrocytomas have a good prognosis and with timely treatment, patients can live long and healthy lives [4].

Medulloblastoma

Medulloblastoma is the second most common pediatric brain tumor and comprises about 10-20% of all pediatric brain tumors. It is a very aggressive tumor that metastasizes throughout the central nervous system very early on in the disease. In the United States, about 250 patients are diagnosed with pediatric medulloblastoma every year. The incidence rate for this tumor is 5 cases per million children. The disease peaks around the age of three to five years and 80% of the patients develop this disease in the first 15 years [5].

Patients are divided into three categories and the prognosis for this disease depends on three characteristics:

  • age,
  • removal of tumor and
  • state of metastasis.

The first category is average-risk patients, which includes patients that are three years and older, with non-metastasized disease and have a tumor that is less than 1.5 cm2 after surgery. Patients in this category have a survival that is higher than 80%.

Patients that are classified in the poor-risk category are patients that are aged older than three years with a tumor that has metastasized and a tumor size of more than than 1.5 cm2 post-surgery. The survival for these patients is lower, at approximately 30-60%.

The last category is the infant category which has the worst prognosis of all. Patients in this category are aged less than three years old. The stage of metastasis and the tumor size are irrelevant and the survival for these children is only about 30% [6].

The treatment for this tumor includes surgery to remove the tumor as well as radiation therapy for treatment of brain tumors in children and chemotherapy for treatment of brain tumors in children.

With a combination of these treatments, more than half the patients with medulloblastoma have a 5-year disease-free survival. If the tumor has not metastasized, then these treatments can lead to survival for 80-90% of the patients.

Unfortunately, these treatments are very aggressive and often lead to neurocognitive and endocrinology deficits. While most long term patients do have normal cognition, many of these patients develop long-term disabilities and require personalized education programs. Most survivors do suffer from growth deficiency due to the use of craniospinal radiation, which is the main treatment for these tumors [7]. 

Ependymomas

Ependymomas are the third most common type of brain tumors in children, and comprises 10% of all childhood brain tumors. The average age of diagnosis is five years, with 30-40% of patients being diagnosed under the age of three. In the United States, there are generally about 140 cases that arise per year. In the UK, there are about 30 children per year and in Europe, there are about 300 pediatric patients diagnosed with this tumor per year [8].

It is more severe than astrocytomas but with surgery and radio- and chemotherapy, the overall survival rate is approximately 55%, but the survival rate can go up to 80%. However, age and the degree of tumor removal are indicators of prognosis.

For example, in children that are less than 1 year of age, the survival rate is only 25% while it goes up to 46% for children between the ages of one and four and can be more than 70% in children aged five years and older.

Approximately 85% of patients are able to undergo surgery which results in either total or almost complete removal of the tumor. Upon the removal the tumor, patients then undergo radiotherapy which results in high survival rates of 60-80%. Unfortunately, patients that are unable to undergo full removal have much lower survival rates of less than 30% [9]. In cases with higher grade ependymomas, the size of the tumor can cause neurocognitive as well as hormonal deficits [10].

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