Introduction to Brain Tumor

Executive Summary

The brain consists of three regions involving the cerebrum, brainstem and cerebellum. A brain tumor is the collection or mass of abnormal cells in the brain. The skull enclosing the brain is rigid, and any growth in such a restricted region causes problems in the brain. Brain tumors can be cancerous (malignant) and non-cancerous (benign). The benign tumor tends to increase the pressure inside the skull. It results in brain damage which can be life-threatening. The growth of the brain tumor depends upon the location of the brain tumor, and its impact on the functioning of the nervous system.

Primary brain tumors and secondary brain tumors are the two types of brain tumors. Primary brain tumors can develop from brain cells, meninges, nerve cells or glands and are classified as glioma and non-glioma tumor types. Astrocytomas, Oligodendroglioma, ependymoma, and brain stem glioma are the types of glioma tumor. The non-glioma tumors involve Meningioma, Primary CNS lymphoma, Medulloblastoma, Pineal and pituitary tumors, Schwannoma, Craniopharyngioma.

What is Brain Tumor?

It can be shocking and life-changing for people diagnosed with a brain tumor. If you are suspected of having a brain tumor, you should seek the opinion of doctors who specialize in diagnosing brain tumors.

Brain Tumor Surgery: Types and Treatments ~ Healthcare In India

About the Brain and Central Nervous system

The brain has three parts:

The cerebrum, the brainstem and the cerebellum are the three parts of human brain. The meninges are protective layers around the brain that are also considered a part of the brain. 

The cerebrum

The cerebrum is the most significant part of the brain, having two hemispheres; the right and left. It is divided into four lobes performing specific functions.

The frontal lobe controls reasoning, emotion, problem-solving, movement and expressive speech.

The parietal lobe controls sensations to touch, such as pressure, pain and temperature. It also controls part of speech, visual-spatial orientation and calculation.

The temporal lobe controls special senses such as hearing, speech comprehension and memory.

The occipital lobe controls vision.

The cerebellum

It is mainly responsible for coordination and balance and controls function on the same side of the body. 

The Brain Stem

This part of the brain connects the spinal cord and the cerebellum. It controls involuntary actions essential for our lives, such as breathing and beating the heart. 


These are three-layered, comprising dura mater, arachnoid and pia mater surrounding the brain and spinal cord. The cerebrospinal fluid or CSF is made near the brain’s lateral ventricles. The Cerebrospinal fluid flows between the arachnoid and pia layers around the brain and spinal cord.

Also Read: Integrative cancer treatment

Brain tumor

A Brain tumor starts when normal and healthy cells grow uncontrollably and form a tumor mass. Our skull is rigid, and any growth can create problems. 

Brain tumors can be cancerous (malignant) or non-cancerous (benign). When benign or malignant tumors grow, they can increase the pressure inside your skull. It can lead to brain damage, and it can be life-threatening ​1​.

How quickly a brain tumor grows can vary greatly. The growth rate, and the location of a brain tumor, determine how it will affect the function of your nervous system.

A brain tumor is usually classified into two types:

  1. Primary brain tumors are those that originate in the brain. These can be benign or cancerous ​2​.
  2. Secondary brain tumors have metastasized to the brain from other body parts, such as the lungs or breast ​3​

If cancer proliferates to the meninges and the Cerebrospinal fluid (CSF), it is called leptomeningeal metastases or neoplastic meningitis. More commonly, this condition is seen in leukemia, lymphoma, melanoma, breast cancer, or lung cancer.  

Types of Primary Brain tumor

Primary brain tumors can develop from brain cells, meninges, nerve cells or glands ​4​.

Descriptions of more common brain tumor types in adults are described below, divided into glioma and non-glioma tumor types.


Glioma is the tumor of brain cells called the glial cells, which are supportive brain cells.

Glial cells of the brain hold nerve cells in position, bring nutrition and oxygen to neurons, and help protect them from disease, like an infection. 

Currently, the types of glioma include ​5​


Astrocytoma is the most common type of glioma. Astrocytomas are more common in children than in adults. 


Oligodendroglioma cells look like oligodendrocytes which make myelin sheath in CNS. They are categorized as either oligodendroglioma, considered low grade, or anaplastic oligodendroglioma, a high-grade tumor.


Ependymoma usually begins where CSF is made and stored. They occur more often in the spine in adults and can also be of the myxopapillary subtype. 

Brain stem glioma 

A brain stem glioma begins in the glial cells in the brain stem.


Non-glioma tumors are tumors that arise from cells in the brain that are not glial cells. Types of nonglioma tumors include ​6​:


Meningioma is the most common primary brain tumor. It starts in the meninges and is most often non-cancerous. Meningioma can generate severe symptoms if it grows and presses on the brain or spinal cord or grows into the brain tissue. 

Primary CNS lymphoma 

Lymphoma is a cancer that starts in the lymphatic system. Primary CNS lymphoma begins in the brain and can extend to the spinal fluid and eyes.


Medulloblastoma probably starts from a particular cell called cerebellar granule progenitor cells in the cerebellum. It is commonly seen in children and is usually cancerous, often spreading throughout the CNS. 

The pineal and pituitary gland tumors

These are tumors that start in the pineal gland and pituitary gland.


Schwannoma is a rare tumor that begins in the nerve sheath or the lining of the nerves. It is typically non-cancerous.


Craniopharyngioma is a benign tumor that begins near the pituitary gland located near the base of the brain. These tumors are rare.


  1. 1.
    Herholz K, Langen KJ, Schiepers C, Mountz JM. Brain Tumors. Seminars in Nuclear Medicine. Published online November 2012:356-370. doi:10.1053/j.semnuclmed.2012.06.001
  2. 2.
    Aldape K, Brindle KM, Chesler L, et al. Challenges to curing primary brain tumours. Nat Rev Clin Oncol. Published online February 7, 2019:509-520. doi:10.1038/s41571-019-0177-5
  3. 3.
    Bertolini F, Spallanzani A, Fontana A, Depenni R, Luppi G. Brain metastases: an overview. CNS Oncology. Published online January 2015:37-46. doi:10.2217/cns.14.51
  4. 4.
    Chandana S, Movva S, Arora M, Singh T. Primary brain tumors in adults. Am Fam Physician. 2008;77(10):1423-1430.
  5. 5.
    Schneider T, Mawrin C, Scherlach C, Skalej M, Firsching R. Gliomas in Adults. Deutsches Ärzteblatt international. Published online November 12, 2010. doi:10.3238/arztebl.2010.0799
  6. 6.
    Forst DA, Nahed BV, Loeffler JS, Batchelor TT. Low-Grade Gliomas. The Oncologist. Published online March 24, 2014:403-413. doi:10.1634/theoncologist.2013-0345