Brain Tumors: An Overview
A brain tumor, also known as an intracranial tumor, is an abnormal mass of tissue in the brain where cells grow and multiply uncontrollably. This growth is unchecked by the mechanisms that control normal cells. Brain tumors can be either benign (non-cancerous) or malignant (cancerous). Tumors may originate in the brain (primary tumors) or spread to the brain from other parts of the body (secondary tumors or brain metastasis). More than 120 different types of tumors can develop in the brain.
While the cause of most brain tumors is unknown, risk factors include exposure to certain chemicals, viruses, radiation, and inherited syndromes.
Tumors can be graded on a scale of 1-4, according to their severity. grade 1 tumors are the least severe and associated with long-term survival, while grades 3 and 4 are aggressively malignant.
The most common primary brain tumors are gliomas (including astrocytomas, oligodendrogliomas, and ependymomas), meningiomas, pituitary adenomas, and nerve sheath tumors.
Astrocytomas: A Closer look
Astrocytomas are a type of brain tumor that originates from astrocytes, which are star-shaped glial cells in the brain and spinal cord. They are the most common type of glioma and, in adults, the most common brain tumor. Astrocytomas are graded by the World Health Organization (WHO) on a scale of 1 to 4, based on characteristics such as atypia, mitosis, endothelial proliferation, and necrosis. grade I astrocytomas are the least aggressive and associated with long-term survival, while grade 4 astrocytomas are the most aggressive. The grades help determine the severity of the astrocytoma and the best treatment options.
WHO grading of central nervous system tumors
Grade 1 includes lesions with low proliferative potential and a frequently discrete non-infiltrative nature; surgical resection is the main treatment.
Grade 2 includes lesions that are infiltrating and low in mitotic activity, but recur. Some tumor types tend to progress to higher grades of malignancy.
Grade 3 includes lesions with histologic evidence of malignancy, generally in the form of mitotic activity, clearly expressed infiltrative capabilities, and anaplasia.
Grade 4 includes lesions that are mitotically active with vascular proliferation, necrosis-prone, and generally associated with a rapid pre-operative and post-operative evolution of disease.
The exact cause of astrocytomas is unknown, but researchers speculate that genetic and immunologic abnormalities, environmental factors, diet, and stress may play a role.
Astrocytomas are more common in adults, typically developing between the ages of 30 and 50. In children, they usually develop between 5 and 9 years of age.
Limited treatment options for patients with grade 3 astrocytoma
For patients with radiographically (MRI) suspected grade 3 astrocytoma, surgery is the initial recommended approach for reducing tumor size and pathologic diagnosis. After surgery, adjuvant radiation therapy is generally considered to be the standard of care.
After surgery and radiation therapy (RT), patients typically receive some form of chemotherapy (e.g. temozolomide or Temodar®). Currently, there are limited options for physicians treating grade 3 astrocytoma with chemotherapy. The available chemotherapies provide some benefit to patients, but effect is modest and toxicity limit long-term use. There have been no new treatment options since the FDA approval of temozolomide in 1999.
Since there is a need for better treatment options for patients diagnosed with astrocytoma, we are developing eflornithine for grade 3 astrocytoma patients who have progressed or recurred following surgery, RT and chemo.