Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Anaplastic astrocytoma ?
    ### Response:
    Anaplastic astrocytoma is a rare, cancerous (malignant) type of brain tumor that arises from star-shaped brain cells called astrocytes. These cells surround and protect nerve cells in the brain and spinal cord. An anaplastic astrocytoma usually develops slowly over time, but may develop rapidly.
    