A brain tumor, known as an intracranial tumor, is an abnormal mass of tissue in which cells grow and multiply uncontrollably, seemingly unchecked by the mechanisms that control normal cells. More than 150 different brain tumors have been documented, but the two main groups of brain tumors are termed primary and metastatic.
PRIMARY BRAIN TUMORS
Primary brain tumors include tumors that originate from the tissues of the brain, or the brain’s immediate surroundings. Primary tumors are categorized as glial (composed of glial cells) or non-glial (developed on or in the structures of the brain, including nerves, blood vessels and glands) and benign or malignant.
METASTATIC BRAIN TUMORS
Metastatic brain tumors include tumors that arise elsewhere in the body (such as the breast or lungs) and migrate to the brain, usually through the bloodstream. Metastatic tumors are considered cancer and are malignant.
Metastatic tumors to the brain affect nearly one in four patients with cancer, or an estimated 150,000 people a year. Up to 40 percent of people with lung cancer will develop metastatic brain tumors. In the past, the outcome for patients diagnosed with these tumors was very poor, with typical survival rates of just several weeks.
The National Cancer Institute estimates that 22,910 adults (12,630 men and 10,280 women) will be diagnosed with brain and other nervous system tumors in 2012. It also estimates that in 2012, 13,700 of these diagnoses will result in death.
Between 2005 and 2009, the median age for death from cancer of the brain and other areas of the nervous system was age 64.
Pituitary adenomas are the most common intracranial tumors after gliomas, meningiomas and schwannomas. The large majority of pituitary adenomas are benign and fairly slow-growing. Even malignant pituitary tumors rarely spread to other parts of the body. Adenomas are by far the most common disease affecting the pituitary. They commonly affect people in their 30s or 40s, although they are diagnosed in children, as well. Most of these tumors can be treated successfully.
Schwannomas are common benign brain tumors in adults. They arise along nerves, comprised of cells that normally provide the “electrical insulation” for the nerve cells. Schwannomas often displace the remainder of the normal nerve instead of invading it. Acoustic neuromas are the most common schwannoma, arising from the eighth cranial nerve, or vestibularcochlear nerve, which travels from the brain to the ear. Although these tumors are benign, they can cause serious complications and even death if they grow and exert pressure on nerves and eventually on the brain. Other locations include the spine and, more rarely, along nerves that go to the limbs.
Gliomas are the most prevalent type of adult brain tumor, accounting for 78 percent of malignant brain tumors. They arise from the supporting cells of the brain, called the glia. These cells are subdivided into astrocytes, ependymal cells and oligodendroglial cells (or oligos). Glial tumors include the following: Glioblastoma multiforme (GBM)
Glioblastoma multiforme is the most invasive type of glial tumor. These tumors tend to grow rapidly, spread to other tissue and have a poor prognosis. They may be composed of several different kinds of cells, such as astrocytes and oligodendrocytes. GBM is more common in people ages 50 to 70, and more prevalent in men than women.
- Headaches that may be more severe in the morning
- Seizures or convulsions
- Difficulty thinking, speaking or articulating
- Personality changes
- Weakness or paralysis in one part or one side of the body
- Loss of balance or dizziness
- Vision changes
- Hearing changes
- Facial numbness or tingling
- Nausea or vomiting
- Confusion and disorientation
Diagnostic tools include CT scans and MRI. Sometimes the only way to make a definitive diagnosis of a brain tumor is through a biopsy or tumor resection. The neurosurgeon performs the biopsy and the pathologist makes the final diagnosis, determining whether the tumor appears benign or malignant, and grading it accordingly.
Brain Tumor Treatment
Brain tumors (whether primary or metastatic, benign or malignant) usually are treated with surgery, radiation, and/or chemotherapy — alone or in various combinations. While it is true that radiation and chemotherapy are used more often for malignant, residual or recurrent tumors, decisions as to what treatment to use are made on a case-by-case basis and depend on a number of factors. There are risks and side effects associated with each type of therapy.
The goal of surgery is to remove as much tumor as possible, without injuring brain tissue important to the patient’s neurological function (such as the ability to speak, walk, etc.). Traditionally, neurosurgeons open the skull through a craniotomy to insure they can access the tumor and remove as much of it as possible.
In many cases, surgical navigation systems provide intraoperative guidance to pinpoint the tumor and permit excision with acceptable risks.