Tumor Grades and Types
Tumor Grade
Types of Primary Brain Tumors
When most normal cells grow old or get damaged,
they die, and new cells take their place. Sometimes,
this process goes wrong. New cells form when the
body doesn't need them, and old or damaged cells
don't die as they should. The buildup of extra cells
often forms a mass of tissue called a growth or tumor.
Primary brain tumors can be benign or malignant:
- Benign brain tumors do not contain cancer cells:
- Usually, benign tumors can be removed, and they
seldom grow back.
- Benign brain tumors usually have an obvious
border or edge. Cells from benign tumors rarely
invade tissues around them. They don't spread to
other parts of the body. However, benign tumors
can press on sensitive areas of the brain and
cause serious health problems.
- Unlike benign tumors in most other parts of the
body, benign brain tumors are sometimes life
threatening.
- Benign brain tumors may become malignant.
- Malignant brain tumors (also called brain cancer)
contain cancer cells:
- Malignant brain tumors are generally more
serious and often are a threat to life.
- They are likely to grow rapidly and crowd or
invade the nearby healthy brain tissue.
- Cancer cells may break away from malignant
brain tumors and spread to other parts of the
brain or to the spinal cord. They rarely spread to
other parts of the body.
Doctors group brain tumors by grade. The grade of
a tumor refers to the way the cells look under a
microscope:
- Grade I: The tissue is benign. The cells look nearly
like normal brain cells, and they grow slowly.
- Grade II: The tissue is malignant. The cells look
less like normal cells than do the cells in a Grade I
tumor.
- Grade III: The malignant tissue has cells that look
very different from normal cells. The abnormal cells
are actively growing (anaplastic).
- Grade IV: The malignant tissue has cells that look
most abnormal and tend to grow quickly.
Cells from low-grade tumors (grades I and II) look
more normal and generally grow more slowly than
cells from high-grade tumors (grades III and IV).
Over time, a low-grade tumor may become a highgrade
tumor. However, the change to a high-grade
tumor happens more often among adults than children.
You may want to read the NCI fact sheet
Tumor Grade.
There are many types of primary brain tumors.
Primary brain tumors are named according to the type
of cells or the part of the brain in which they begin.
For example, most primary brain tumors begin in glial
cells. This type of tumor is called a glioma.
Among adults, the most common types are:
- Astrocytoma: The tumor arises from star-shaped
glial cells called astrocytes. It can be any grade. In
adults, an astrocytoma most often arises in the
cerebrum.
- Grade I or II astrocytoma: It may be called a
low-grade glioma.
- Grade III astrocytoma: It's sometimes called a
high-grade or an anaplastic astrocytoma.
- Grade IV astrocytoma: It may be called a
glioblastoma or malignant astrocytic glioma.
- Meningioma: The tumor arises in the meninges. It
can be grade I, II, or III. It's usually benign (grade I)
and grows slowly.
- Oligodendroglioma: The tumor arises from cells
that make the fatty substance that covers and
protects nerves. It usually occurs in the cerebrum.
It's most common in middle-aged adults. It can be
grade II or III.
Among children, the most common types are:
- Medulloblastoma: The tumor usually arises in the
cerebellum. It's sometimes called a
primitive neuroectodermal tumor. It is grade IV.
- Grade I or II astrocytoma: In children, this lowgrade
tumor occurs anywhere in the brain. The most
common astrocytoma among children is juvenile pilocytic astrocytoma. It's grade I.
-
Ependymoma: The tumor arises from cells that line
the ventricles or the central canal of the spinal cord.
It's most commonly found in children and young
adults. It can be grade I, II, or III.
- Brain stem glioma: The tumor occurs in the lowest
part of the brain. It can be a low-grade or high-grade
tumor. The most common type is diffuse intrinsic pontine glioma .
You can find more information about types of brain
tumors at
http://www.cancer.gov/cancertopics/types/brain. Or, you can call the NCI Cancer Information Service
at 1-800-4-CANCER (1-800-422-6237).
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