Brain tumors are the most common solid tumors in pediatrics. The number of new annual cases is estimated at about 30 cases per million. There are several types of brain tumors depending on the cell from which the tumor originates. Gliomas thus come from cells that support neurons, namely astrocytes or oligodendrocytes. These tumors, very frequent among pediatric tumors, are of different grades: low-grade glioma, anaplastic glioma, and glioblastoma (which notably includes midline gliomas or infiltrating brainstem gliomas).
Descriptions, diagnoses, and treatments
Pilocytic Astrocytomas
Pilocytic astrocytoma, grade I, specific to children, is a tumor that most often evolves slowly and whose growth can spontaneously stop after adolescence. Pilocytic astrocytomas can develop anywhere in the central nervous system, from the optic nerve to the end of the spinal cord. It is the most frequently observed glial tumor in children. There is a predisposition syndrome for pilocytic astrocytomas, neurofibromatosis type 1, a rare disease (30% of cases). This manifests as café-au-lait spots, learning difficulties, and sometimes (5% of cases) a tumor, especially in the optic pathways.
Pilocytic astrocytomas are more frequently found in the cerebellum and optic pathways. Clinical symptoms are primarily visual and difficult to diagnose in young children. The first-line treatment is surgical removal followed by chemotherapy. Many drugs are effective in this disease, starting with those with the least long-term toxicity. After a first line of treatment, the risk of recurrence remains unfortunately significant. In case of failure of one or more chemotherapies, irradiation treatment may be considered if the child is old enough, preferably with techniques that best preserve healthy tissues, such as proton therapy.
Other Low-Grade Gliomas
There are many other low-grade or “benign” gliomas that are often treated similarly to pilocytic astrocytomas, i.e., surgery first, followed by chemotherapy if necessary. In particular:
- Dysembryoplastic neuroepithelial tumors (DNET), which usually present with epilepsy and rarely need treatment other than surgery.
- Gangliogliomas, which respond less well to chemotherapy but for which drugs targeting a frequently found BRAF gene mutation in these tumors are under development.
High-Grade or “Malignant” Gliomas
Our understanding of these tumors has considerably advanced in recent years, particularly thanks to the BIOMEDE project that we have strongly supported. We now know that children’s malignant gliomas are very different from adult forms, and this distinction must now guide future therapeutic strategies. Very specific mutations, never described in another cancer, of genes regulating DNA organization and expression have been recently described in these tumors.
Infiltrating brainstem gliomas and midline gliomas are treated differently from other malignant gliomas. Their location in critical brain regions (such as the brainstem) and their infiltrating nature make any surgical attempt difficult or even impossible. They are biopsied to confirm the diagnosis, perform the tumor’s molecular profile, and thus provide the most suitable treatments for the patient. Moreover, radiotherapy is systematically used at the maximum possible dose (55-60 Gy) and generally limited to the tumor volume itself. Unfortunately, few chemotherapies have proven effective in high-grade gliomas. Children are most often treated within clinical trials or benefit from experimental treatments under early access or compassionate use.
Ependymomas
These tumors are one of the three most common malignant brain tumors in children and usually appear before the age of 5. They are most frequently located in the posterior fossa, at the cerebellum level, but can be found in all other brain areas. Surgery is a crucial element in the treatment of ependymomas, and multiple interventions are often necessary to achieve complete tumor removal. The role of chemotherapy is still being tested in clinical trials to determine if it can improve radiotherapy’s effectiveness. Few drugs have proven effective, and studies are ongoing to develop new treatments more targeted at the tumor’s carcinogenesis mechanisms.
What are the symptoms?
Since there are many types of brain tumors that can also be located in different brain areas, the symptoms can vary significantly. They depend mainly on the location, size, growth rate of the tumor, the child’s age, and development stage. Symptoms can be subtle or even ordinary, may appear and disappear, or be similar to those of other childhood diseases. Hence, diagnosis is often difficult and can take several weeks. Prolonged or recurring pain, associated with neurological signs, should raise suspicion of a brain or spinal cord tumor.
Observed symptoms include:
- Headaches, often more intense in the morning
- Nausea and vomiting, often in the morning
- Seizures
- Changes in personality or behavior
- Irritability or loss of interest in normal daily activities
- Vision problems, such as strabismus, double vision, or slightly blurred vision
- A strong desire to sleep or significant drowsiness without reason
- Altered activity level or fatigue more quickly than usual
- Weakness or numbness on one side of the face or body
- Weakness or clumsiness, such as difficulty walking or maintaining balance
- Difficulty speaking or swallowing
- Hearing difficulties
- Early or delayed puberty
- Delayed or abnormal growth or development
- Regression of motor skills
- Increase in head size in infants
These symptoms alone are not sufficient for diagnosis. Only imaging tests, or even a biopsy, will provide an accurate diagnosis and determine the tumor’s nature, location, and aggressiveness. These symptoms, unfortunately, are common to other pathologies. At the slightest doubt or if one or more of these symptoms persist, we advise you to consult your doctor, who will refer the child for appropriate diagnostic tests and specialists.
Research Against Gliomas with Imagine for Margo
Since 2011, Imagine for Margo has prioritized research against cancer in children, adolescents, and young adults. Indeed, given the current situation, the association funds numerous research programs to cure more and better the young affected by cancer. Among these, you can find programs concerning gliomas:
Today’s research on all forms of childhood gliomas should further improve the management of this disease by increasing treatment effectiveness and reducing side effects.
Moreover, the European initiative Fight Kids Cancer, which we initiated, launched this year a specific call for projects for central nervous system tumors. We hope to put an end to these high-risk cancers.
If you wish to help research and build a world with cancer-free children, please donate by clicking here. Every gesture is essential in our fight for life.
Together, we will defeat childhood and adolescent cancer.
Bibliography
https://www.ipubli.inserm.fr/bitstream/handle/10608/102/Chapitre_23.html
https://www.gustaveroussy.fr/fr/gliomes
