Most brain tumors are sporadic, meaning they have no known cause. The only known risk factors for primary brain tumors are environmental, such as ionizing radiation, or immune suppression. People with certain rare genetic disorders (von Hippel Lindau disease, neurofibromatosis type 2) also have an increased risk of developing certain brain tumors.
How Brain Tumors are Diagnosed
There are no screening tests to detect brain tumors early, and most are detected only once patient has symptoms. Diagnostic investigation begins with obtaining a thorough history and physical exam, followed by imaging studies (CT, MRI). PET scan is occasionally used. Although many brain tumors can be seen with a CT scan or MRI, a stereotactic biopsy is sometimes needed to confirm the diagnosis and type of tumor. A small hole is drilled into the skull and a needle is inserted to obtain a sample of the tumor for inspection under a microscope.
Treatment Options for Brain Tumors at Tufts Medical Center
Given great diversity of primary brain tumors, treatments are complex and frequently require close consultation and coordination by specialists from neurosurgery, neuro-oncology, radiation oncology, neuroradiology and neuropathology. Treatment includes surgery, radiation therapy, and chemotherapy, often in combination.
Surgery is the most common treatment for brain tumors. It is the treatment of choice for any brain tumor that can be reached without causing damage to normal tissue. In case of more aggressive brain cancers, complete removal of the tumor is frequently not possible, and surgery is done to “debulk” or reduce the tumor as much as possible. Goals include improvement of neurologic function, relief of symptoms; extend in duration and quality of life.
Stereotactic surgery is performed either with a frame or without one. When a frame is used—a special lightweight metal ring is attached to the head with 4 small pins after the skin is anesthetized. The patient then gets an MRI scan in the frame. The MRI images are then sent to a special computer that will, under the surgeon’s direction, determine the exact location or coordinates of the tumor. Most often this is used for a needle biopsy of a brain lesion where high precision is required. The frameless stereotactic surgery is performed without a frame. A high resolution MRI is obtained and loaded onto a computer navigation system in the operating room. In the operating room the patient’s head is then matched with the MRI. Once this is done a wireless pen is then used to very accurately localize any structure on or in the patient’s head. With this the neurosurgeon can design a small incision and skull opening (craniotomy) right where it needs to be and find the shortest and safest route to remove the brain tumor with the least amount of brain disruption.
Surgery may be combined with radiation therapy or followed with chemotherapy to destroy any remaining cancer cells.
New methods allow physicians to raise the dose of radiation delivered to a tumor, while minimizing the amount of radiation that reaches healthy tissue.
Gamma Knife is “brain surgery without the knife”. Gamma knife applies extremely precise and focused radiation beams to the brain tumor, while the surrounding brain is spared the high doses of radiation. Gamma Knife is used to treat many conditions including brain metastases from all types of cancers, meningiomas, acoustic neuroma (vestibular schwannoma), pituitary adenomas, chordomas, chondrosarcomas, and some gliomas. The Gamma Knife is done as an outpatient procedure—the patient comes in the morning of the procedure and usually leaves in the afternoon. At Tufts Medical Center we have the only Gamma Knife unit in Massachusetts and Northern New England.
Very few chemotherapy drugs can go through the blood-brain barrier – a natural barrier that protects the brain by not allowing the toxins to reach the brain tissue. Temozolomide (Temodar), a pill given orally, is a targeted therapy that can overcome this obstacle. It interferes with cell division, slowing tumor growth. Temodar has been shown to prolong survival and improve quality of life in patients with Glioblastomas.