What Is a Brain Tumor?

How many different types of brain tumors are there?

Brain tumors originate when cells grow abnormally in or near the brain. Brain tumors can be dangerous to your health and well-being even if they are benign, or noncancerous. Fewer than 30 percent of all brain tumors are malignant, or cancerous. However, most noncancerous brain tumors cause symptoms and may require treatment.

According to the American Brain Tumor Association, there are more than 120 types of brain tumors and central nervous system (CNS) tumors. Brain tumors can be categorized in many different ways. At Neurosurgery One, we classify brain tumors in three different groups: primary, metastatic, and tumors that develop outside of the brain and push on the brain.

Primary Brain Tumors

Primary brain tumors originate in the brain. Approximately 17,000 new cases of primary brain tumors are treated each year in the United States. Primary brain tumors can be benign or malignant. While anyone can develop primary brain tumors, people are most commonly diagnosed with a primary brain tumor at ages 40-70.

Gliomas are the most common type of primary brain tumor in adults. They are usually cancerous, though not always. Gliomas form in the glial cells, which are non-neural cells in the central nervous system that support homeostasis and function. One type of a glioma tumor is known as astrocytoma, which is a tumor that arises from astrocyte cells — part of the supportive (neuroglial) tissue of the brain. Astrocytomas account for about half of all primary brain and spinal cord tumors.

Metastatic Brain Tumors

Metastatic tumors in the brain, or brain mets, are caused by cancerous cells that shed from tumors in other parts of the body, travel through the bloodstream, burrow through the blood vessel walls, latch onto tissue, and create new tumors inside the brain or spinal cord. While nearly every type of cancer can spread to the brain, the most common types that lead to metastatic brain tumors are melanoma (skin cancer), breast, lung, colon, and renal cancers. Nearly 200,000 patients in the U.S. are diagnosed with metastatic brain tumors annually, making it far more common than tumors that originate in the brain.

Brain Tumors That Originate Outside of the Brain and Push on the Brain

The most common type of brain tumors that develop outside of the brain and then push on the brain are called meningiomas. These tumors originate in the membranes that surround the brain and spinal cord. The majority of meningiomas are benign.

Pituitary tumors are another common form of tumor that originate outside of the brain and push on the brain. Pituitary tumors develop in the pituitary gland and are most commonly benign. They account for 10 percent of all brain tumors.

What are types of skull base tumors?

Deriving its name from the location of the tumor, skull base tumors grow in the bottom of the head area, which includes the lower skull bones and bony area behind the eyes and nose. Skull base tumors can be classified by their location in the skull base (known as the cranial fossa) — anterior cranial fossa, central cranial fossa, and posterior cranial fossa — or type of tumor. Skull base tumors can be benign or malignant.

Meningiomas are the most common type of skull base tumors and are typically found in the anterior cranial fossa and central cranial fossa. Pituitary adenomas and schwannomas can develop in the central cranial fossa.

Acoustic neuromas are typically found in the posterior cranial fossa. An acoustic neuroma is a benign (noncancerous) skull base tumor that starts in the cells that wrap around the auditory (hearing) and vestibular (balance) nerves in the head. These tumors may grow on one or both sides of the brain. Acoustic neuromas account for about 7 percent of all brain tumors. Acoustic neuromas are a form of schwannoma. This means it is a tumor that originates in the cells that form a protective sheath around the body’s nerve fibers. Acoustic neuromas are also known as vestibular schwannomas.

What are treatment options for brain tumors and skull base tumors?

Treatment of brain tumors and skull base tumors depends on the location and size of the tumor, type of tumor, and your health. Physicians typically require imaging tests to provide more insight about the tumor and treatment options. Imaging tests that a Neurosurgery One neurosurgeon may recommend include MRI, CT, functional MRI (fMRI), PET, or fiber tractography. If a metastatic tumor is suspected, your physician may recommend a CT or PET to determine where the cancer originated. At Neurosurgery One, we work closely with our patients’ medical oncologists and radiation oncologists to pinpoint the appropriate treatment plan for metastatic tumors and malignant primary brain tumors.

Benign brain tumors — such as meningiomas, acoustic neuromas, and pituitary gland tumors — and some gliomas usually grow slowly and can often be treated with surgery or stereotactic radiosurgery (Gamma Knife), depending upon their specific location in the brain.

Malignant brain tumors, such as glioblastomas and anaplastic astrocytomas, among others, tend to grow rapidly, spreading into the surrounding brain tissue, and often cannot be entirely removed surgically. Glioblastomas can be difficult to treat, although surgery, radiation therapy, steroids. and chemotherapy have been clearly shown to prolong survival. In addition, Neurosurgery One offers Optune, an FDA-approved therapy for the treatment of newly diagnosed and recurrent glioblastoma. Read more about Optune and who is a candidate.

Meningiomas often are treated with surgery or Gamma Knife radiosurgery, whereas many pituitary tumors don’t require treatment. For pituitary tumors that cause symptoms and require treatment, surgery may be an option. Medications are generally the recommended treatment for prolactinoma tumors, which are pituitary tumors that result in an excess of the prolactin hormone.

Metastatic brain tumors can be treated with conventional (whole brain) radiation, although metastatic tumors are often better treated with surgery or radiosurgery. According to research, Gamma Knife radiosurgery has been found to be as effective as surgical approaches in smaller metastases. Radiosurgery has also been shown to provide effective and predictable control of single and multiple brain metastases even in traditionally radioresistant metastases like renal cancer or melanoma. Radiosurgery or surgery are often preferred over whole brain radiation for patients with single brain metastasis, as it results in better quality of life, local control of the tumor, and increased cognitive function.

Many skull base tumors require surgery, particularly if the tumor is causing pressure.

Based on the type and location of the brain or skull base tumor, treatment options may include:

• Minimally invasive procedures. Minimally invasive endoscopic surgery may be an option for some skull base tumors on the anterior skull base and pituitary tumors. Keyhole craniotomy, another minimally invasive brain tumor surgery, is most often recommended for skull base tumors, meningiomas, acoustic neuromas, and some metastatic brain tumors.
• Stereotactic radiosurgery. Despite its name, Gamma Knife stereotactic radiosurgery is not a surgery. Rather, this procedure utilizes radiation to specifically target the tumor. Gamma Knife radiosurgery can be completed in an outpatient setting in one day, unlike other radiation therapies that often require several rounds of treatment. Gamma Knife stereotactic radiosurgery is often recommended for cancerous and noncancerous tumors that are either small in size or number, or difficult to access through traditional surgery. This treatment may also be recommended for arteriovenous fistula (AVF), metastatic tumors, acoustic neuromas, pituitary tumors, and trigeminal neuralgia. Patients who undergo Gamma Knife stereotactic radiosurgery may have sores from the headframe put in place to guide the radiation. Most patients can control their pain from the procedure with acetaminophen (Tylenol). Other stereotactic radiosurgery procedures can be conducted without the headframe. Complication rates are known to be lower with radiosurgery than open surgery.
• Optune. For patients 22 and older with newly diagnosed and recurrent glioblastoma, Neurosurgery One offers the FDA-approved portable and wearable Optune.
• Chemotherapy. Most chemotherapy medications do not penetrate the blood/brain barrier and are not effective in brain tumor treatment. However, chemotherapy may be pursued to control the primary cancer if the disease originated outside of the brain.
• Radiation. When possible, targeted stereotactic radiosurgery is generally recommended as a first step before full brain radiation is pursued to minimize side effects, including cognitive function and quality of life.
• Brain surgery. Craniotomy is the most common brain surgery recommended for operable brain tumors. Read more about brain tumor and skull base surgeries offered by Neurosurgery One.