Metastatic Brain Tumors: What You Need to Know
Metastatic brain tumors (also called secondary brain tumors) are caused by cancer cells spreading (metastasizing) to the brain from a different part of the body.
The cancer cells break away from the primary tumor and travel to the brain, usually through the bloodstream, then commonly go to the part of the brain called the cerebral hemispheres or to the cerebellum. Cancer can also spread to the spine (metastatic spine tumors).
Metastatic brain tumors are five times more common than primary brain tumors (those that originate in the brain).
Metastatic brain tumors can grow rapidly, crowding or destroying nearby brain tissue. Sometimes a patient may have multiple metastatic tumors in several different areas of the brain.
What happens when cancer spreads to the brain?
The most common types of cancer that cause metastatic brain tumors are cancers of the lung, breast, skin (melanoma), colon, kidney and thyroid gland.
Some metastatic brain tumors appear many years after the primary cancer. Others metastasize so quickly that they are identified before the primary cancer.
In other cases, the body is able to destroy the primary cancer but not the metastatic brain tumor. When this occurs, the primary cancer can be unknown.
What are the signs and symptoms of metastatic brain tumor?
Common signs and symptoms
What are the risk factors for metastatic brain tumor?
About one third of patients with another type of cancer will develop one or more metastatic brain tumors. The risk for metastatic brain tumors begins to increase after age 45 and is highest in those over 65.
How are metastatic brain tumors diagnosed?
Metastatic brain and spine tumors are not usually diagnosed until symptoms appear. Here are some ways doctors may diagnose a metastatic brain tumor:
Physical exam: After gathering information about your symptoms and personal and family health history, the doctor proceeds with a physical exam and vision and reflex tests.
(CT or CAT scan)
Magnetic resonance imaging
Functional magnetic resonance imaging (fMRI)
Diffusion tensor imaging (DTI): This scan allows the surgeon and treating team to visualize the circuitry (or wiring) of the brain to guide the surgery. These images can then be loaded into navigation systems that are used in the operating room to serve as a kind of GPS and map for the surgeon.
More Information on Metastatic Brain Tumors from Johns Hopkins Medicine
Novel Lab Device Provides Window into Cancer Metastasis
There’s no technology that can observe how cancer cells hop aboard the bloodstream and migrate to other places in the body, so Peter Searson and grad student Andrew Wong set out to build a device that simulates how cancer spreads
Online Seminar: Updates in Treatment Options for Brain Metastases
Cancer spreads to the brain in as many as one third of patients with primary lung, breast, kidney, colon and skin cancers. Neurosurgeon Dr. Michael Lim talks about metastatic brain tumors how to navigate the brain before and during surgery.
Metastatic Brain Tumor Treatment
It is important to know that metastatic brain tumors are often treatable and can be well controlled.
Optimal treatment for metastatic brain or spine tumors is tailored to each patient. The neurosurgeon determines the most appropriate treatment approach, considering these factors:
The type of primary cancer the patient has, response to treatment and current status
The location and number of metastatic tumors within the brain or spine
The patient’s general health and preferences regarding potential treatment options
The patient's current symptoms
Surgery provides fast relief of “mass effect” — pressure inside the skull resulting from a growing tumor and swelling of the brain. Patients can experience improvement within hours of surgery if mass effect is what is causing their symptoms.
The goal of surgery is to minimize the amount of space the tumor takes up by debulking, removing as much of the tumor as possible while maintaining the patient’s neurological function.
In general, doctors recommend surgery when:
There is a clear correlation of neurologic deficits with the tumor’s location
The patient’s primary cancer is treatable and under control
A patient has one or two metastatic brain tumors, or a few tumors that are close to each other that can be safely removed
The most common type of surgery to remove metastatic brain tumors is called a craniotomy, which can be performed through a variety of approaches, including the keyhole craniotomy.
The surgeon may choose a microsurgery procedure, and use newer tools — such as image-guided surgery and minimally invasive endoscopy — to ensure the best chance for a good outcome.
Radiation therapy is the treatment of tumors using X-rays and other forms of radiation (light energy) to destroy cancer cells or prevent a tumor from growing. It is also called radiotherapy.
These painless treatments involve passing beams of radiation through the body, which can treat cancers in areas of the brain that are difficult to reach through surgery. Procedures may include any one or combination of the following:
These procedures may also be performed after surgery to prevent tumors from growing near the site of the tumor removal and into other brain tissue.
Choosing radiation therapy is complex and often involves a team approach. Some patients receive a form of radiation therapy called stereotactic radiosurgery instead of surgery. Other patients will receive whole-brain radiation or a combination of both therapies, depending on what the treatment team determines is best.
The Radiation Team
Treatment planning for radiation therapy includes mapping to pinpoint the exact location of the tumor using X-rays or other images.
A radiation oncologist uses these images to create a three-dimensional picture of the patient’s brain. For some types of radiation therapy, a custom-fitted mask is created to increase the precision of the treatment. Fiducials — small markers temporarily attached to the scalp — may also be used.
A radiation oncologist then designs the patient’s treatment, determining the most appropriate radiation dose (the level of radiation energy to be used) and delivery method.
A dosimetrist or medical physicist (professionals who specialize in using radiation therapy equipment and calculating and measuring radiation) will calculate the dose, the angle of the treatment beam and the amount of time for each beam. After they work with the radiation oncologist to review the calculations, the treatments can be scheduled.
Because traditional chemotherapy cannot cross the blood-brain barrier, a new treatment called targeted therapy is used as the primary type of chemotherapy for treating metastatic brain tumors.
These drugs identify and attack cancer cells (the target) with minimal harm to normal cells while preventing the growth and spread of cancer cells. Targeted therapy can be administered after surgery or in conjunction with radiation therapy to destroy remaining cancer cells.
Targeted therapies used to treat metastatic brain tumors include: