The brain and spinal column make up the central nervous system (CNS), where all vital functions of the body are controlled. When tumors arise in the central nervous system, they are especially problematic because a persons thought processes and movements can be affected. These tumors can also be difficult to treat because the tissues surrounding a tumor that may be affected by surgery or radiation may play a vital role in functioning.

There are two broad types of cancers occurring within this system. Primary tumors originate in the central nervous system, whereas secondary tumors migrate from cancers located elsewhere in the body, such as breast cancers. Secondary, or metastatic, brain tumors, are more common than primary brain cancers. This section focuses on primary brain cancers.

What is the brain?

Together, the brain and spinal cord form the central nervous system. This complex system is part of everything we do. It controls the things we choose to do,like walk and talk,and the things our body does automatically,like breathe and digest food. The central nervous system is also involved with our senses; seeing, hearing, touching, tasting, and smelling, as well as our emotions, thoughts, and memory.

The brain is a soft, spongy mass of nerve cells and supportive tissue. It has three major parts: the cerebrum, the cerebellum, and the brain stem. The parts work together, but each has special functions.

The brain is composed of:

A. The cerebrum, which is divided into two cerebral hemispheres. The cerebrum is the largest part of the brain and is divided into lobes where discrete functions occur. Higher reasoning takes place in the cerebrum.

B. The cerebellum, or little brain, located beneath the cerebrum. The cerebellum controls coordination and balance.

C. The brain stem, which is the lowest portion of the brain and connects to the spinal cord, controls involuntary functions essential for life, such as the beating of the heart and breathing.

D. The meninges, membranes that surround and protect the brain and spinal cord. There are three meninges.

The types of primary brain cancers are classified according to the type of cells from which they originate. Oncologists describe the tumor based on its characteristics. For example, a noninfiltrating tumor can be expected to grow slowly and not invade surrounding structures. A well-differentiated tumor is also slow growing, but has the potential to be invasive. Anaplastic tumors are generally more aggressive.

Gliomas - Most brain tumors are gliomas, which originate in the glial cells (the supportive cells of the nervous system). Gliomas can be described as low-grade (slow-growing); intermediate-grade (more aggressive); or high-grade (very aggressive).

There are many different types of gliomas:

E. Astrocytoma, the most common type of glioma, which usually begin in cells called astrocytes within the cerebrum, or the cerebellum. Glioblastoma multiforme is a form of very aggressive astrocytoma.

F. Oligodendroglioma, a tumor that develops from oligodendrocytes. These cells are responsible for producing the myelin that surrounds nerves.

G. Brain stem glioma, which begins in the glial cells in the brain stem.

H. Ependymoma, which begins in the ependyma, the cells that line the passageways in the brain where cerebrospinal fluid is made and stored.

I. Mixed tumors, which are composed of more than one of the glial cell types.

Nonglial tumors include:

J. Acoustic schwannoma, which occurs in the vestibular nerve.

K. Craniopharyngioma, which begins near the pituitary gland.

L. Meningiomas, which originate in the meninges surrounding the brain and spinal column. Even though these tumors are generally benign, they may cause significant symptoms as they grow and press on the brain or spinal cord.

M. Medulloblastoma, which arises from granular cells in the cerebellum.

N. Primary CNS lymphoma.

O. The pineal and pituitary glands, located near the base of the brain, can also be the source of tumors.

Since brain and spinal cord tumors behave somewhat differently than tumors arising in other parts of the body, they are often referred to as low and high grade, rather than benign and malignant. Oncologists assign the terms low, intermediate, or high grade to a patient’s tumor based on parameters that predict how quickly the tumor can grow and its potential to spread to other parts of the brain.

Treating brain and spinal cord tumors can be difficult. The blood-brain barrier, which normally serves to protect the brain and spinal cord from damaging chemicals getting into those structures, also keeps out many types of potentially beneficial chemotherapy drugs. Surgery can be difficult if the tumor is near a delicate portion of the brain or spinal cord and radiation therapy can damage healthy tissue. However, research in the past two decades has improved the survival rates of patients with brain tumors. More refined surgeries, a better understanding of what types of tumors respond to chemotherapy, and precise delivery of radiation have resulted in longer life span and better quality of life for people with brain cancers.

As we well know, there are many kinds of cancer; unfortunately they all come about because of the out-of-control growth of abnormal cells.