Primary Brain Tumors

A brain tumor is a mass of abnormal cells in the brain. Some tumors are caused by inherited genetic conditions, such as neurofibromatosis, von Hippel-Lindau disease and tuberous sclerosis, but most occur because of changes in genes that have yet to be fully understood by researchers.

Primary tumors are growths that start in the brain (metastatic tumors are caused by cancer that has travelled to the brain from another place in the body). All brain tumors are either benign – meaning they are not cancerous – or malignant, meaning they are cancerous. However, brain tumors can cause serious damage even when they are benign. The tumors listed below are some of the most common types of primary brain tumors.

Gliomas

These tumors arise from glial cells and can occur in the regions of the brain that control functions like movement, speech, thought and emotion. They can also affect the brain stem — the lower part of the brain that controls functions like breathing, blood pressure and heartbeat — as well as optic nerves and the cerebellum. Some gliomas are caused by genetic disorders; exposure to radiation may also play a factor. The vast majority of gliomas are cancerous. Types of gliomas include: 

  • Glioblastomas are the most aggressive and fastest growing cancerous brain tumor. They are the most common type of brain tumor. 
  • Astrocytomas are cancerous tumors that grow from spider-shaped cells called astrocytes in the brain or spine. They can be slow or fast-growing, depending on the type.
  • Oligodendrogliomas start in cells called oligodendrocytes, which help form the fatty covering of nerve cells in the brain or spinal cord. These cancerous tumors tend to be slow growing.
  • Ependymomas usually grow slowly and may be found in the brain or spinal cord. Ependymomas occur when ependymal cells – a type of glial cell that lines the chambers of the brain that contain cushioning fluid – grow uncontrollably.

Meningiomas

Meningiomas are one of the most common tumors in the brain area. Most are non-cancerous; the tumors grow in the meninges, which are the membranes lining the skull and spinal canal. Because they can compress the brain and spine, their size and location can cause neurological problems like headaches, seizures and even loss of smell. These tumors can occur along the skull base beneath the brain. Skull base meningiomas can be challenging to surgically remove because of their location.

Pineal Tumors

A pineal tumor is a tumor of the pineal gland, which secretes melatonin, a substance that affects your sleep-wake cycles. These very rare tumors happen most often to children and adults younger than 40. They can cause problems by pressing against other parts of the brain, and they can also block the normal flow of fluid that bathes your brain and spine, causing increased pressure, headaches, nausea and vomiting. Pineal tumors include pineocytomas, pineoblastomas and mixed pineal tumors.

 

Skull Base Tumors

The skull base refers to the bottom part of your skull, upon which rests the brain. Tumors located at the skull base involve delicate blood vessels, nerves and other structures. If left untreated, skull base tumors can lead to serious consequences, such as blindness or stroke. Types of skull base tumors include:

  • Pituitary Tumors: A pituitary tumor is an abnormal growth in the pituitary gland, a small gland located behind your nose that makes hormones affecting other glands and bodily functions. Most pituitary tumors are non-cancerous and do not spread to other parts of the body; some, however, cause the pituitary to make too few or too many hormones, which causes problems. The tumors can also press against the nearby optic nerves, which triggers vision problems. If a pituitary tumor isn’t causing noticeable symptoms, it may not be discovered until a routine brain imaging or blood test occurs. 
  • Acoustic neuroma: An acoustic neuroma is a rare, noncancerous tumor that grows slowly and tends to affect patients in middle age. This tumor presses on the inner ear’s hearing and balance nerves; a large tumor may press on a person’s facial nerve or brain structures. Patients may experience hearing loss on one side, ringing in the ears, dizziness, facial numbness, tingling or headaches. Unilateral acoustic neuromas affect only one ear, while bilateral acoustic neuromas affect both and are caused by an inherited genetic disorder, neurofibromatosis-2.
  • Chordomas: Chordomas are a rare form of bone cancer that occur along the length of the spine, including the base of the skull. Skull-base chordomas commonly affect the nerves that control movement of the face, eyes and swallowing. Symptoms include pain or changes in nerve function, headache, face/neck pain, double vision, facial numbness or paralysis, changes in speech or swallowing problems. 

Metastatic (Secondary) Brain Tumors

A metastatic brain tumor is cancer that started elsewhere in the body that has spread to the brain. For instance, a tumor can start in the lung, then spread to the brain—even if the cancer is controlled at the original site. These types of brain tumors are also called secondary tumors. In adults, they are more common than tumors that originate in the brain. 

Cancer can spread to the brain through your lymph system, bloodstream or nearby tissue. In most cases, metastatic brain tumors are found in the cerebrum, the outer part of the brain that controls your thoughts, emotions and language ability.