The National Cancer Institute estimates that in 2010, doctors will diagnose 22,020 people in the United States with a brain tumor. These brain tumors can be benign or malignant. If a patient has a cancerous brain tumor, the cancer receives a grade ranging from I to IV based on its malignancy.
The American Association of Neurological Surgeons explains that the World Health Organization developed a brain tumor grading system with four grades: grade I and grade II tumors are considered low grade tumors, while grade III and grade IV are considered high-grade tumors. Grade IV or stage 4 brain cancer is the most malignant form of brain cancer. The doctor assigns the grade to the cancer after looking at a sample of the tumor taken during a biopsy.
A grade IV brain tumor has certain characteristics that distinguishes it from other brain cancer stages. For example, the American Association of Neurological Surgeons notes that grade IV brain tumors grow rapidly and spread to affect other tissue. A doctor can note the rapid growth by observing mitosis in the biopsy sample, in which the cells divide and replicate. John W. Henson, MD, of the Brain Tumor Center from Massachusetts General Hospital and Harvard Medical School, adds that grade IV brain tumors outgrow their blood supply, called necrosis. A doctor may also notice new blood vessels growing in the sample of tissue.
Several types of brain cancers are classified as grade IV. An example includes an ependymoblastoma, a type of cancer found in infants and young children. Ependymoblastomas usually occur in the ventricles of the brain, which are areas of the brain that contain cerebrospinal fluid. The National Cancer Institute points out that glioblastoma multiforme makes up 12 percent to 15 percent of brain cancers. Glioblastoma multiforme occurs in the cerebral hemisphere and arises from astrocytes, a type of glial cell in the brain. Pineoblastomas occur in the pineal gland, while medulloblastomas, a type of brain cancer found in children, form in the cerebellum.
Henson explains that doctors treat grade IV brain tumors with chemotherapy, surgery and radiation. After diagnosis, the doctor will start the treatment soon, as a grade IV brain cancer grows quickly. The treatment may begin with surgery, in which the surgeon opens the skull and removes as much of the tumor as possible without damaging nearby brain tissue. Within two to four weeks of the surgery, grade IV brain cancer patients receive radiation or chemotherapy. Radiation therapy uses ionized radiation targeted at the tumor, while chemotherapy uses one or more drugs that destroy the cancerous cells. The doctor will use an MRI scan to monitor the tumor and the progression of the treatment.
The prognosis for a grade IV brain tumor depends on the tumor. For example, the National Cancer Institute notes that 88 percent of pineoblastoma patients survive one year, 78 percent of patients survive three years and 58 percent of patients survive five years. In comparison, patients with an ependymoblastoma die within six to 12 months of their diagnosis. The five-year survival rate for a medulloblastoma ranges between 50 percent and 70 percent, according to the National Cancer Institute. With a glioblastoma multiforme, the National Cancer Institute explains that the average time patients live with the cancer is less than a year.