Brain Cancer (Tumor)
When brains cells grow abnormally, they can form a mass called a tumor.
Some brain tumors are non-cancerous, or benign. Cells from benign tumors rarely spread through the tissues around them or to other parts of the body.
Although benign tumors are not usually life-threatening, they can grow and destroy and compress normal brain tissue, causing damage to the brain.
Cancer of the brain occurs when a tumor is malignant (cancerous). There are two types of brain cancer: primary and metastatic. Primary brain cancer starts in the brain while metastatic cancer is a cancer that has spread to the brain from another part of the body.
A malignant primary brain tumor (brain cancer) rarely spreads to other parts of the body, but it can spread through brain tissue, crowding and invading healthy tissue.
The chance that a person will develop a malignant brain tumor in his or her lifetime is less than 1 percent: about 1 in 140 for a man and 1 in 180 for a woman.
Common symptoms include:
- Changes in your ability to talk, hear or see
- Headaches, usually worse in the morning
- Problems with thinking or memory
- Nausea and vomiting
- Numbness or tingling in arms or legs
- Difficulty with balance or walking
- Muscle jerking or twitching
Doctors group brain tumors by grade, which is the way the cells look under a microscope:
Grade I (tissue is benign): The cells closely resemble normal brain cells, and they grow slowly.
Grade II (tissue is malignant): The cells look less like normal cells than do the cells in a grade I tumor.
Grade III (tissue is malignant): The malignant tissue has cells that look very different from normal cells, and the abnormal cells are actively growing (anaplastic).
Grade IV (tissue is malignant): The malignant tissue has cells that look most abnormal and tend to grow quickly.
Primary brain tumors are named for the brain cell or part of the brain in which they began. Among adults, the most common types are:
Most primary brain tumors start in the glial cells and account for about 3 out of 10 brain tumors. Astrocytomas arise from star-shaped glial cells called astrocytes, which help support and nourish neurons.
In adults, an astrocytoma most often occurs in the cerebrum, which is the front part of the brain that controls reading, thinking, learning, speech and emotions. There are different grades:
- Grade I or II astrocytoma (low-grade glioma)
- Grade III astrocytoma (high-grade or an anaplastic astrocytoma)
- Grade IV astrocytoma (glioblastoma or malignant astrocytic glioma)
The tumor arises in the meninges: the layers of tissue that surround the outer part of the brain and spinal cord. Meningiomas can be grade I, II or III; however, most are usually benign (grade I) and grow slowly.
This tumor arises from cells called oligodendrocytes that make myelin—the fatty substance that covers and protects nerves. It usually occurs in the cerebrum and is most common in middle-aged adults. It can be grade II or III.