Anaplastic Astrocytoma · What Is It, Causes, Signs, and More

Anaplastic astrocytomas are rare, malignant brain tumors that arise from astrocytes, a star-shaped cell that surrounds and protects nerve cells in the central nervous system (CNS). Anaplastic refers to cancer cells that divide rapidly and do not resemble healthy cells, and astrocytes are a type of glial cell and make up the majority of cells in the human CNS. Glial cells are responsible for supporting, connecting, and protecting the neurons of the central and peripheral nervous system. Tumors arising from glial tissue, including astrocytomas, are collectively known as gliomas. 

The World Health Organization (WHO) classifies astrocytomas based on how fast the cells reproduce and the likelihood of infiltration into nearby tissues. According to this classification, anaplastic astrocytomas are grade III and are considered high-grade (i.e., degree of abnormality among cells when viewed microscopically). This is in contrast with grade I or II astrocytomas which are circumscribed and low-grade, or grade IV astrocytomas which are also known as glioblastoma multiforme (GBM), which are the most aggressive form of astrocytomas. Low-grade astrocytomas can transform into high-grade astrocytomas over time.

The exact cause of anaplastic astrocytoma is unknown, however, it is thought to arise from a combination of genetic and environmental factors. Genetic mutations in astrocytes can lead to uncontrolled cell growth which underlies the pathophysiology of anaplastic astrocytomas. Additionally, mutations in tumor suppressor genes (e.g., TP53) can increase genetic susceptibility to astrocytomas. Environmental factors may also trigger these genetic changes, including exposure to ultraviolet rays, chemicals, and ionizing radiation, as well as diet (e.g., cured meats that contain high levels of N-nitroso compounds [NOCs]) and stress. A general risk factor for developing brain tumors includes a family history of brain tumors. Additionally, astrocytomas occur at a greater frequency in those with certain genetic disorders (e.g., neurofibromatosis type I, Li-Fraumeni syndrome, tuberous sclerosis).  

Anaplastic astrocytomas affect genetic males more than genetic females and are more common in adults compared to children. The average age is typically between 30 and 50 years, whereas in children, they develop between 5 and 9 years of age.  

Treatment of anaplastic astrocytomas frequently involves a team of specialists, which may consist of an oncologist, radiation oncologist, neurosurgeon, neurologist, nurses, and other healthcare professionals. The specific therapies utilized can vary depending on the size, location, grade, and stage (i.e., the spread or infiltration) of the tumor.  

Initial treatment options for anaplastic astrocytoma typically consist of surgical excision and resection, or removal of the bulk of the tumor to preserve and improve quality of life. If the tumor cells have spread into surrounding brain tissue, radiation can be used to treat possible residual cancer. If surgery is not an option due to factors such as the location of the tumor and the individual’s age, radiation therapy alone may be used. Chemotherapy with anticancer drugs such as temozolomide can be used in conjunction with radiation to treat anaplastic astrocytoma. Temozolomide is the only drug approved by the Food and Drug Administration (FDA) for treatment in adults with refractory anaplastic astrocytoma, which has not responded to other forms of therapy. At this time, there are no chemotherapeutic agents approved for the treatment of children with anaplastic astrocytoma, however, clinical trials and experimental therapies are currently underway.