Begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.
Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.
What are benign and malignant brain tumors?
Brain tumors can be benign or malignant:
* Benign brain tumors do not contain cancer cells:
o Usually, benign tumors can be removed, and they seldom grow back.
o The border or edge of a benign brain tumor can be clearly seen. Cells from benign tumors do not invade tissues around them or spread to other parts of the body. However, benign tumors can press on sensitive areas of the brain and cause serious health problems.
o Unlike benign tumors in most other parts of the body, benign brain tumors are sometimes life threatening.
o Very rarely, a benign brain tumor may become malignant.
* Malignant brain tumors contain cancer cells:
o Malignant brain tumors are generally more serious and often are life threatening.
o They are likely to grow rapidly and crowd or invade the surrounding healthy brain tissue.
o Very rarely, cancer cells may break away from a malignant brain tumor and spread to other parts of the brain, to the spinal cord, or even to other parts of the body. The spread of cancer is called metastasis.
o Sometimes, a malignant tumor does not extend into healthy tissue. The tumor may be contained within a layer of tissue. Or the bones of the skull or another structure in the head may confine it. This kind of tumor is called encapsulated.
Tumor Grade
Doctors sometimes group brain tumors by grade - from low grade (grade I) to high grade (grade IV). The grade of a tumor refers to the way the cells look under a microscope. Cells from high-grade tumors look more abnormal and generally grow faster than cells from low-grade tumors.
