There are four astrocytoma grades — numbered 1-4 — provided by the World Health Organization (WHO). This grading system was first introduced in 1993. Until that point, diagnosing astrocytomas was a confusing process. Each of the four grades uses the aggressiveness of the brain neoplasm for classification. Using the WHO guidelines, the astrocytomas are graded by specific characteristics.
Astrocytoma is a form of neoplasm found in the brain. The growths occur in specific brain cells of the cerebrum, known as astrocytes. Unlike many other tumors, astrocytomas do not have the potential to metastasize outside the brain and spinal cord. Astrocytes are only in the cerebrum.
Among the astrocytoma grades, Grade 1 is used to classify astrocytomas that are the least aggressive. The tumors grow slowly and are benign. Surgical removal is likely, allowing complete remission to occur. Pilocytic astrocytoma is one type that falls in this grade, and it is commonly found in children.
Grade 2 is the second of the astrocytoma grades. It is used to classify astrocytomas that are still slowly growing but are slightly more aggressive than Grade 1 astrocytomas. The growths can become malignant and more aggressive. Surgical removal is not likely because the tumor cells tend to penetrate through tissue into normal, unaffected areas.
Next in the four astrocytoma grades is Grade 3. Anaplastic astrocytomas fall into this grade. Neurological problems, mental instability, seizures and headaches are often present. Removing as much of the tumor as possible can help relieve symptoms. Radiation therapy can treat the remaining tumor.
Grade 4 is the most aggressive of the astrocytoma grades. Glioblastoma multiforme (GBM) is the most common astrocytoma in this grade. These astrocytomas grow very quickly and can be quite large before they are detected. Symptoms do not usually occur immediately but will begin with seizures. Surgical removal is performed only when neurological injury can be avoided.
The treatment for tumors in any of the astrocytoma grades includes removal as the first line of defense, whenever possible. For low-grade astrocytomas, surgical removal followed by radiation or chemotherapy increases survival rates. High-grade astrocytomas are more difficult to treat because the tumor cells are invasive. Surgery can remove large parts of the cells, but radiation and chemotherapy must be used in higher amounts to delay regrowth of the remaining cells.
Concentrated radiation can be used to treat specific areas where tumors have appeared. It is often chosen when astrocytoma has not metastasized into secondary tumors. Chemotherapy is recommended when primary astrocytoma has spread to other parts of the body. Chemotherapy enters the body through the bloodstream and therefore can be a widespread treatment.