What Is Brain Cancer?

March 2020

Reviewed By: Charles Patrick Davis, MD, PhD


Brain cancer is a malignant growth of abnormal brain cells in the brain. A grouping of abnormal cells is called a tumor. Some tumors are benign and some are malignant. There are several different types of tumors that occur in the brain and spinal cord. different cells in the brain and spinal cord give rise to various kinds of tumors. Spinal cord tumors and brain tumors may grow quickly or slowly. Even benign tumors may cause symptoms. The brain is the central organ that governs other organs and systems in the body, so all brain tumors need to be taken seriously.

Brain Tumor Dangers

The skull is a hard framework of bone. Tumors in the brain are dangerous because they press on areas of the brain as they grow. The skull is not able to expand to accommodate the presence of a tumor. When the tumor grows, it presses on the brain. Depending on which area of the brain is affected, this may cause problems with thinking, acting, seeing, and feeling. Factors that determine how dangerous a brain tumor is include the location, whether or not it can be surgically removed, and how quickly it grows, and whether or not it has the ability to spread.

What Is Secondary Brain Cancer?

Approximately 200,000 to 300,000 people per year in the U.S. suffer from tumors that start elsewhere in the body and then spread, or metastasize, to the brain. Approximately 50% of cancers found in the brain begin as lung cancer that later spreads to other organs including the brain. Other cancers that may spread to the brain include those of the colon, breast, kidney, and melanoma, a potentially deadly type of skin cancer. At least 80% of tumors in the brain occur as multiple growths in the brain. Another 10% to 20% of tumors that have metastasized to the brain are single tumors.

Main Primary Brain Tumors

Primary brain tumors begin in the brain cells. Meningiomas are the primary brain tumors that are the most common. More than 35% of primary brain tumors are meningiomas.? These tumors come from tissue that covers the brain and spinal cord. The next most common type of tumor in the brain is a glioma. Glioma occur in the gluey, supportive tissue of the brain. Nearly 25% of primary brain tumors are gliomas. Glioblastomas are the next most common type of primary brain tumor. They are a type of glioma and they comprise almost 15% of all primary brain tumors. They comprise more than 55% of all gliomas. Senator John McCain was diagnosed with a primary glioblastoma.

Other Types of Primary Brain Tumors

Meningiomas, gliomas, and glioblastomas are the main kinds of primary brain tumors but there are others. They arise from different areas in the brain. Adenomas are tumors that occur in the pituitary gland. Chordomas are primary brain tumors that occur in the spine and skull. Sarcomas are primary brain tumors that arise from the dura (a meninx, a tissue layer that lines the spine and skull), cartilage, or bones. Medulloblastomas are primary brain tumors that arise from the cerebellum, which is the part of the brain in the back of the skull.

What Are the Different Grades of Brain Tumors?

Brain tumor grade describes how aggressive a tumor is and how likely it is to spread. Brain tumors may be given a grade of 1 through 4. The lower the grade of a tumor, the better the expected prognosis. Grade 1 brain tumors are considered low grade. They grow slowly, are the least malignant (noncancerous) cells, and are unlikely to spread. Surgically removing these tumors may be curative. Grade 2 tumors have slightly abnormal cells, but they do not contain dead cells or actively dividing cells. Grade 2 tumors are not generally cancerous. Grade 3 tumors are cancerous and contain actively dividing abnormal brain cells. Grade 4 tumors are considered high grade and they are aggressive and cancerous.

Symptoms of a Brain Tumor

Brain tumor symptoms differ depending on the type of growth that the patient has and where it is located in the brain. Symptoms may include unusual behavior, confusion, sleep difficulties, seizures, and balance problems. People with brain tumors may suffer from vision changes, nausea, vomiting, hearing loss, twitching, and memory problems. Some people may even get seizures and lose consciousness. Other symptoms may include muscle weakness, numbness, personality changes, and paralysis. Some people with brain tumors develop headaches that are often worse in the morning.