The brain is made up of many different types of cells. Brain cancers occur when one type of cell transforms from its normal characteristics and grows and multiplies in an abnormal way.

Primary tumor:

Brain tumors that result from this transformation and abnormal growth of brain cells are called primary brain tumors because they originate in the brain. Usually they are named after the part of the brain or the type of brain cell from which they arise. Many of them are benign and can be successfully removed. Malignant primary brain tumors cause problems by spreading into the normal brain tissue thereby increasing the pressure and causing damage to the surrounding areas of the brain. These tumors rarely spread outside the brain to other parts of the body. The most common primary brain tumors are gliomas. They begin in glial cells. There are many types of gliomas:

Astrocytoma: The tumor arises from star-shaped glial cells called astrocytes. In adults, astrocytomas most often arise in the cerebrum. In children, they occur in the brain stem, the cerebrum, and the cerebellum.

Brain stem glioma: The tumor occurs in the lowest part of the brain. Brain stem gliomas most often are diagnosed in young children and middle-aged adults.

Ependymoma: The tumor arises from cells that line the ventricles or the central canal of the spinal cord. They are most commonly found in children and young adults.

Oligodendroglioma: This rare tumor arises from cells that make the fatty substance that covers and protects the nerves. These tumors usually occur in the cerebrum. They grow slowly and usually do not spread into surrounding brain tissue. They are most common in middle-aged adults.

Other primary tumors that do not begin in the glial cells are

Medulloblastoma or primitive neuroectodermal tumor: This tumor usually arises in the cerebellum. Rarely do these tumors spread outside the brain. It is the most common brain tumor in children.

Meningioma: This tumor arises in the meninges and grows slowly. Meningioma are benign and do not spread from their original site. Malignant meningiomas are very rare.

Schwannoma: This tumor arises from the Schwann cells. These cells line the nerve that controls balance and hearing. This nerve is in the inner ear. The tumor is also called an acoustic neuroma. It occurs most often in adults. They are more common in people who have a genetic disease called neurofibromatosis type 2.

Craniopharyngioma: The tumor grows at the base of the brain, near the pituitary gland. This type of tumor most often occurs in children.

Haemangioblastoma: This is a rare type of tumor that develops from cells that line the blood vessels. They are benign and grow slowly

Pituitary tumors: These types of tumors develop in the Pituitary gland. They are benign and are called pituitary adenomas.

Germ cell tumor of the brain: The tumor arises from a germ cell. Most germ cell tumors that arise in the brain occur in people younger than 30 years. The most common type of germ cell tumor of the brain is a germinoma.

Pineal region tumor: This rare brain tumor arises in or near the pineal gland. The pineal gland is located between the cerebrum and the cerebellum. The most common tumors are germinomas, teratomas, pineocytomas and pineoblastomas.

Secondary tumors:

Secondary brain tumors or metastatic tumor occur when cancer cells from other parts of the body, such as the lung, breast, skin, kidney, colon spread to the brain. These tumor cells reach the brain via the blood-stream. Secondary tumors in the brain are far more common than primary brain tumors. About 25% of tumors elsewhere in the body metastasize to the brain.

Childhood brain tumor:

Brain tumors are the most common solid tumors that occur in children. Children of any age may be affected. Boys are affected more often than girls. Two types of brain cancers that are more common in children than in adults are medulloblastoma and ependymoma. Treatment and chance of recovery depend on the type of tumor, its location within the brain, the extent to which it has spread, and the child's age and general health.