Astrocytoma

Overview

An astrocytoma refers to a cluster of cells that originates within the brain or spinal cord. This cluster, often referred to as a tumor, develops from specific cells known as astrocytes. Astrocytes play a vital role in providing support and facilitating communication among nerve cells in both the brain and spinal cord.

Signs and symptoms of astrocytoma differ based on the specific location of the tumor. A brain astrocytoma has the potential to cause personality changes, seizures, migraines, and nausea. If the astrocytoma develops within the spinal cord, it may result in weakness and diminished ability in the area affected by the developing tumor.

Certain astrocytomas exhibit a gradual growth pattern. These noncancerous growths are occasionally referred to as benign astrocytomas. The majority of astrocytomas experience rapid growth and are classified as brain cancers. These are occasionally denoted as malignant astrocytomas. The determination of whether the tumor is benign or malignant constitutes a pivotal aspect in deciding the treatment plan by the medical team.

Type

Astrocytomas have the capacity to manifest as either benign or malignant variants. The World Health Organization (WHO) employs a categorization system that divides astrocytomas into four grades. This classification hinges on the pace of astrocytoma growth and their propensity to infiltrate neighboring brain tissue. The mildest forms are classified as grade 1 astrocytomas, whereas grade 4 astrocytomas epitomize the most aggressive type.

• Noncancerous astrocytoms:
  • Grade 1 astrocytomas: The following are the noncancerous form of astrocytomas:
    • Pilocytic astrocytoma: Pilocytic astrocytomas commonly develop within the cerebellum. This tumor grows slowly and normally does not have the tendency to spread to other organs. This type of tumor is most common in grade 1 astrocytomas. It is not malignant, thus chemotherapy or radiation treatments are not necessary after surgical removal.
    • Pleomorphic xanthoastrocytoma: This specific tumor typically appears in the temporal lobe and has a slow growth. It frequently causes seizure. Typically, surgery is a curative measure for this form of brain tumor.
    • Subependymal giant cell astrocytoma (SEGA): This tumor develops in the ventricles. It is typically seen in children with the inherited disorder tuberous sclerosis. Surgery is frequently effective in providing a cure.
• Cancerous astrocytomas:
  • Grade 2 astrocytomas: These types of astrocytomas have a tendency to extend into surrounding brain tissue. Due to this behavior, relying solely on surgery may not be sufficient for their treatment.
  • Grade 3 astrocytomas: More aggressive than their grade 2 counterparts, these astrocytomas frequently manifest as an advancement from grade 2 astrocytomas. These tumors are not curable through surgery alone. Their effective management involves the use of radiation therapy and nearly always entails the administration of chemotherapy.
  • Grade 4 astrocytomas (Glioblastomas): These represent the highest grade within the astrocytoma classification. They stand as the prevalent type of astrocytoma and are characterized by their remarkable aggressiveness, displaying rapid growth and spread. They may emerge as a cancerous progression from a pre-existing lower-grade astrocytoma (seen in 10% of cases), or initiate as a grade 4 tumor from the outset (observed in 90% of cases).

Symptoms

The manifestations of astrocytoma can vary based on their size and location. The prevalent symptoms of astrocytoma encompass the following:

• Headaches
• Nausea and vomiting
• Seizures
• Delirium or dementia (altered mental status)
• Loss of memory
• Cognitive issues, such as personality changes or mood changes (like depression).
• Fatigue.
• Problem with visions
• Aphasia or trouble speaking.
• Motor problems, such as abnormal reflexes or weakness.

It is recommended to seek immediate medical attention if an individual is experiencing any of the following signs and symptoms.

Causes

The precise causes of the majority of astrocytomas are still unknown. These tumors typically emerge spontaneously, implying their occurrence is stochastic. Presently, only two established risk factors are associated with astrocytomas: exposure to radiation and genetic predisposition.

Emerging research has revealed that a mutation in the IDH1 gene plays a significant role in the development of low-grade astrocytomas. This specific gene plays a role in cellular energy production. This mutation causes the production of a specific chemical 2-HG, which accumulates within healthy astrocytes over time. This accumulation triggers an abnormal changes of the cells, leading to the formation of astrocytomas.

• Radiation exposure and astrocytomas: Ionizing radiation exposure, such as that provided during radiation therapy, increases the risk of developing an astrocytoma.
  For instance, children who undergo prophylactic radiation for acute lymphocytic leukemia (ALL) may have a 22-fold greater risk of acquiring a tumor of the central nervous system, such as an astrocytoma, within a time frame of roughly five to ten years.
• Genetics and astrocytomas: Astrocytomas are prone to develop in people with the following uncommon genetic conditions:
  • Li-Fraumeni syndrome: In this condition, a change occurs in his TP53 gene. Ninety percent of people with Li-Fraumeni syndrome will likely get one or more cancers at some point in their lifetime, with astrocytoma among those cancers.
  • Neurofibromatosis type 1 (NF1): This disorder leads to abnormal elevations in cell growth, stemming from a mutation in a gene that is designed to inhibit the proliferation of tumors. Astrocytomas, peripheral nerve tumors, and café-au-lait spots on the skin can all develop early in the course of NF1 disease in those who are affected.
  • Tuberous sclerosis: Epilepsy, developmental delays, and the growth of tumors throughout the body are just a few of the medical conditions brought on by this disease. Mutations in the TSC1 and TSC2 genes are the known causes of tuberous sclerosis. Tuberous sclerosis patients are the only ones who frequently get SEGAs (subependymal giant cell astrocytomas).
  • Turcot syndrome: This disorder develops as a result of mutations in numerous genes that prevent tumor growth. In addition to one or more tumors in the brain or spinal cord, like an astrocytoma, Turcot syndrome typically involves the development of polyps in the gastrointestinal tract.