Understanding brain tumors

The words “brain tumor” mean different things to different people. Some may think about glioblastoma, the fast-growing, incurable cancer that claimed the lives of Senator John McCain and Senator Ted Kennedy in recent years. Others may know someone whose benign brain tumor was treated with surgery, radiation, chemotherapy, clinical trials, or other targeted treatments. Still others have been diagnosed with a tiny brain tumor that requires a watch-and-wait approach, rather than treatment.

There are at least 100 different types of brain tumors, according to the National Brain Tumor Society, so their impact on patients’ lives varies considerably.

More than 70 percent of brain tumors are benign (non-cancerous), and nearly 30 percent are malignant (cancerous), according to the National Brain Tumor Society. But those terms don’t provide as much information about the impact that they have on patients as tumor grades do.

Tumor grading assesses how aggressive a brain tumor is expected to be. Brain tumors can be categorized as low-grade (grades I and II) or high-grade (grades III and IV). Grade I tumors are the lowest-grade, slowest-growing and least aggressive. Grade IV tumors are the highest-grade, quickest growing and most aggressive.

“For lower-grade gliomas, the median survival times are much more favorable than for higher-grade gliomas, on the order of decades,” said Dr. Jeffrey Wefel, chief of the neuropsychology section in the neuro-oncology department at the University of Texas MD Anderson Cancer Center in Houston.

Primary and secondary brain tumors

More than 1 million Americans are living with primary brain tumors, and more than 90,000 Americans are diagnosed with primary brain tumors annually, again according to the National Brain Tumor Society.

Primary brain tumors arise from cells in and around the brain. The most commonly diagnosed benign brain tumor in adults is meningioma, according to the American Cancer Society. It arises from the protective covering that surrounds the brain, the meninges. The most diagnosed malignant brain tumor in adults is glioblastoma (GBM), according to the American Cancer Society. It arises from cells that help the brain’s nerves work efficiently, glial cells.

Secondary brain tumors are metastatic cancer: Cancer that has spread to the brain from other parts of the body.

“Technically speaking, the most common tumor in the brain is a metastatic tumor, simply because other cancers – like lung cancer, breast cancer, melanomas – are more common than primary brain cancers,” said Dr. Yoshie Umemura, chief of neuro-oncology at the Ivy Brain Tumor Center at the Barrow Neurological Institute in Phoenix. “Disease management for brain metastases relies on [managing] the primary disease. If it came from breast cancer, you have to address the breast cancer itself, not just the brain.”

Characteristics of brain tumors

By definition, brain tumors are hidden within the skull. Patients often don’t know about their condition until the tumor grows and compresses nerves, blood vessels or brain tissue, causing symptoms such as nausea, vomiting, headache, and more.

Rapidly growing tumors may become life-threatening, even if they’re benign.

“With intracranial disease, there’s not a lot of space to grow within the skull without crowding,” Dr. Umemura said. “[Symptoms] originating from the brain dysfunction itself could be something like seizures, weakness. Or you can have symptoms related to [the] increasing pressure inside the skull.”

Causes of brain tumors

Experts don’t fully understand the cause of brain tumors, but according to the American Cancer Society, they often arise:

  • When patients have inherited gene mutations that are linked to a type of brain tumor.
  • When patients develop certain gene mutations sporadically during their lifetimes.
  • When patients are exposed to radiation, whether from a nuclear disaster or a personal history of medical radiation therapy.

Glioblastomas are most commonly diagnosed in men, according to the American Association of Neurological Surgeons. Other brain tumors may arise more frequently in other people.

“Meningiomas are the only brain tumors that are more common in women and folks of African ancestry,” said Dr. David Raleigh, a radiation oncologist at University of California San Francisco Health in San Francisco. “Meningiomas and glioblastomas can arise in folks who have a history of radiotherapy exposure. For kids, [it’s] almost always genetic diseases without a clear environmental association.”

Different types of brain tumors typically affect children. Pediatric patients tend to have better survival rates than adult patients. (See adult stats vs. children stats for more detail.)

“Medulloblastomas are the most common malignant brain tumors in kids,” Dr. Raleigh said. “Some of these tumors–some ependymomas, some medulloblastomas–have very good long-term outcomes.”

Effects of brain tumor treatments

The most common treatment for brain tumors is surgery. Doctors consider the tumor’s type, grade, size and location before deciding to operate.

When the tumor is operable, a neurosurgeon performs the surgery. They try to remove as much of the tumor as possible without causing injury.

“[Sometimes,] neuropsychologists are in the operating room with the surgeons doing intraoperative monitoring during awake craniotomy,” Dr. Wefel said. “The brain is being stimulated and cognition is being tested to inform the surgeon about the ground truth of resecting certain areas of the brain. [It’s] called onco-functional balance: The desire to have a maximal surgical resection but to also minimize injury or harm to the patient.”

After surgery, patients may receive chemotherapy, radiation, or targeted therapy. Patients also may choose to participate in a clinical trial for medication and/or other treatments under development.

Outcomes vary, based on a patient’s diagnosis and prognosis.

“For glioblastoma, the cells are intermixed with normal cells, [so] it’s impossible to get it all out surgically,” said Dr. Umemura. “We try to resect as much as possible without hurting the patient, [and] we always follow that with radiation and chemotherapy. Despite that, these tumors are not curable, and they always recur.”

Because glioblastoma is so aggressive, patients who are diagnosed with this type of brain tumor live an average of 8 months, according to the National Brain Tumor Society. Some patients live longer, but only 6.9 percent survive for 5 years or more.

Patients with brain tumors such as meningiomas and low-grade astrocytomas may survive for years after treatment. Some experience long-term adverse effects from radiation therapy, such as memory problems, behavioral changes, mood disorders or seizure disorders.

Many pediatric brain tumor patients survive for years after treatment, according to the Pediatric Brain Tumor Foundation. Neuro-oncologists try to keep this in mind when offering treatment modalities that may have lasting effects.

“For kids, we really like to minimize, reduce or, ideally, completely eliminate therapies that can have long-term toxicity, like chemotherapy or ionizing radiation,” Dr. Raleigh said.

How neuropsychologists help brain tumor patients

Neuropsychologists can follow brain tumor patients from diagnosis to treatment and recovery. They help monitor a patient’s cognitive function for evidence of tumor recurrence and help patients cope with changes that arise, including depression, anxiety, fatigue or sleep disruption.

“[Neuropsychologists can] determine the need for accommodations in important life domains, like returning to school, going to work, needing assistance with medication management or financial management, driving safety,” Dr. Wefel said. “[We offer] tailored neuropsychological or neurobehavioral interventions for the patient and for their families, all oriented around the idea of maximizing patient function and well-being and maximizing quality of life.”

This article has been factchecked. For more about that process, click here.