Pediatric low-grade gliomas (PLGGs) are the most common brain and spinal cord tumors affecting children, teenagers, and young adults, accounting for approximately one-third of all central nervous system tumors in this age group. These tumors originate from glial cells, which are supportive cells that surround and nourish neurons. PLGGs are generally considered less aggressive than high-grade gliomas because they grow slowly and rarely spread, often leading to a more favorable outlook for affected children.
Understanding Pediatric Low Grade Glioma
When glial cells grow uncontrollably, they can form a mass known as a glioma. Pediatric low-grade gliomas are classified as “low-grade” because their cells appear less abnormal under a microscope and they exhibit a slow growth rate, making them less likely to invade surrounding tissues aggressively. This distinguishes them from high-grade gliomas, which are characterized by rapid growth and a greater tendency to spread.
PLGGs can develop in various locations throughout the brain and spinal cord. Common sites include the optic pathways, which control vision, the brainstem, responsible for vital functions, and the cerebellum, which manages balance and coordination. They also frequently occur in the cerebral hemispheres, the largest part of the brain involved in functions like movement, speech, and emotion.
There are several subtypes of pediatric low-grade gliomas, each named based on the specific type of glial cell from which they originate. Pilocytic astrocytomas are the most frequent type, often found in the cerebellum or optic pathways. Other subtypes include pleomorphic xanthoastrocytomas and gangliogliomas, which can occur in different brain regions, such as the temporal lobe.
Diagnosis
The initial signs of a pediatric low-grade glioma depend on the tumor’s size and exact location within the brain or spinal cord. Common symptoms that might prompt medical evaluation include persistent headaches, especially those that are worse in the morning, unexplained vomiting, or changes in vision such as blurriness or double vision. Children might also experience balance issues, clumsiness, seizures, or developmental delays.
Diagnosis typically begins with a thorough medical history and a physical and neurological examination by a healthcare provider. If a tumor is suspected, imaging techniques are employed to visualize the brain and spinal cord. Magnetic Resonance Imaging (MRI) is the preferred method for detecting and characterizing these tumors, offering detailed views of the central nervous system. MRI scans can help determine the tumor’s size, location, and relationship to surrounding structures.
While imaging provides strong evidence, a definitive diagnosis of pediatric low-grade glioma typically requires a biopsy. This involves the surgical removal of a small tissue sample from the tumor. A pathologist then examines this tissue under a microscope and performs molecular tests to confirm the tumor type and grade. This detailed analysis is crucial for guiding treatment decisions and understanding the tumor’s specific characteristics.
Treatment Strategies
Treatment for pediatric low-grade gliomas is highly individualized, considering factors such as the tumor’s location, size, the child’s age, and the tumor’s specific molecular characteristics. The primary treatment approach, when feasible, is surgical resection, aiming to remove as much of the tumor as safely possible. Complete surgical removal can be curative for many low-grade gliomas and is often the best predictor of long-term progression-free survival.
However, complete surgical removal is not always possible due to the tumor’s location or its proximity to critical brain structures. In such cases, other treatment modalities become necessary. Chemotherapy, which uses drugs to destroy or shrink tumor cells, is often employed for tumors that cannot be fully removed or are in sensitive areas. Common chemotherapy regimens include combinations of drugs like carboplatin and vincristine, or vinblastine monotherapy, and it may be used to delay or avoid radiation therapy, especially in younger children.
Radiation therapy, which uses high-energy X-rays or other forms of radiation to target and destroy tumor cells, is another option, though it is often considered after surgery and chemotherapy, particularly in younger patients. This is due to potential long-term side effects on the developing brain, such as neurocognitive issues or endocrine problems. Advances in radiation techniques, such as proton beam therapy, aim to reduce these side effects by precisely targeting the tumor while sparing healthy tissue.
Targeted therapies represent a promising development in PLGG treatment. These medicines specifically target unique genetic mutations found within the tumor cells, such as those in the MAPK pathway, which are common drivers of PLGG growth. By blocking these specific pathways, targeted therapies can shrink tumors with potentially fewer side effects than traditional chemotherapy or radiation. These therapies are often oral and can be a first choice in specific cases where the tumor’s molecular profile is known.
Life After Treatment
Children treated for pediatric low-grade gliomas generally have a favorable long-term outlook. Survival rates for these tumors are high, with many children experiencing excellent outcomes and living into adulthood. PLGG is often considered a chronic condition that can be managed effectively.
Following treatment, regular follow-up monitoring is essential to detect any potential recurrence or progression of the tumor. This typically involves periodic MRI scans of the brain and spine, which allow healthcare providers to track the tumor’s status over time. The frequency of these scans is individualized based on the child’s specific case and treatment received.
Despite the generally good prognosis, children may experience long-term effects depending on the tumor’s original location and the treatments administered. These potential effects can include neurocognitive challenges, such as learning difficulties, or endocrine issues, which affect hormone regulation. Vision or motor deficits may also occur. A multidisciplinary team, including neuro-oncologists, neurologists, endocrinologists, and developmental specialists, provides comprehensive ongoing care to address these potential challenges and support the child’s overall well-being.