Understanding brain tumors

There are about 130 different types of brain and central nervous system tumors, ranging from benign (non-cancerous) to malignant (cancerous). Some tumors are extremely rare; others relatively common. Below we discuss the four most common brain tumor types: metastatic, meningioma, glioblastoma and pituitary.

Metastatic brain tumors

Metastatic tumors, the most common brain tumor among adults, are classified as secondary brain tumors. This means they arise from cancer that formed elsewhere in the body and spread to the brain.

Although exact incidence rates are not known, the American Brain Tumor Association estimates between 200,000 and 300,000 metastatic brain tumors are diagnosed each year. Metastatic tumors most often stem from lung or breast cancer.

Larger metastatic tumors are often surgically removed. Smaller tumors may be treated with radiation therapy that focuses beams of radiation onto the tumorous area.

Meningioma

These tumors are technically not brain tumors, since they form in the meninges—membranes that line the skull and vertebral canal. However, their growth may affect the brain by compressing it, causing various disabilities such as vision and hearing impairment, memory loss, or even seizures.

These tumors grow in cycles, sometimes dormant for years, and others growing slowly over a few months.

Most meningiomas are benign. However, if the tumor starts to grow or cause symptoms, physicians will offer treatment that could involve surgical removal or radiation therapy.

Gliomas and glioblastoma

The term glioma is derived from the word “glial,” describing the cell from which this tumor originates in the brain. Glial cells help maintain the health and function of brain cells, or neurons. There are different types of glial cells, with different specific functions. Each cell type has a  name that corresponds to the name of the tumor arising from it. For example, astrocytomas arise from astrocytes and oligodendrogliomas arise from oligodendrocytes.

Brain tumors are not staged. Staging refers to the spread throughout the body, which brain tumors do not do. Brain tumors are graded on a scale of I-IV. The grade indicates how aggressive the tumor tends to behave.

Grade I rarely occurs outside of childhood, where cure is a possibility. There is no cure for grades II-IV.  However, Grade II tumors grow slowly over several years. Grade III is officially considered malignant and can grow over a few years. Grade IV is the most aggressive, and can form in less than one year.

Grade IV tumors are also known as glioblastomas. Their behavior is very aggressive. The most common range of survival is 14-18 months. These tumors are not very common, occurring in 2-3 per 100,000 people per year; compared to 7-14 per 100,000 for metastatic brain tumors.

Treatment options include surgical removal, radiation therapy, chemotherapy, and tumor treating fields. Tumor treating fields are an electric current applied to the scalp that can penetrate through to the brain to disrupt a glioblastoma cell’s ability to divide and grow. 

Our Penn Medicine colleagues in Philadelphia are engaged in clinical trials for glioblastoma. Clinical trials investigate experimental therapies to see if new areas of research will improve how patients feel or how long they live.

Immunotherapy is an area of research showing promise for the treatment of glioblastoma. It works by manipulating a patient’s immune system to attack the tumor. There are also clinical trials investigating new chemotherapies that are more accurate and precise in targeting the tumor. 

In recent years, glioblastoma has made headlines for taking the lives of senators Ted Kennedy and John McCain, as well as Beau Biden, son of former Vice President Joe Biden.

Pituitary brain tumors

These tumors occur in the pituitary gland. This gland literally hangs off the brain, just under the area where the optic nerves meet. The pituitary gland produces hormones that regulate many bodily functions. Pituitary tumors can produce hormones that cause symptoms affecting metabolism, body growth, energy level, and milk production. If a tumor in the pituitary gland grows large enough, it can compress against the optic nerves affecting vision.

The medical term for these tumors is pituitary adenoma. They are typically benign. If they grow or cause symptoms they require treatment. Most types of symptomatic pituitary tumors, except one subtype, are treated surgically by removing through the nose. If the tumor is too large, standard brain surgery is required. 

Most common brain tumor symptoms

Symptoms of brain tumor include persistent headaches, a seizure, progressive weakness on one side of the body, difficulty speaking, or rapidly worsening memory. 

Since headaches are a common occurrence in daily life, talk with your doctor if your headaches:

• Increase in frequency and intensity over days and weeks
• Wake you up when asleep
• Suddenly begin occurring and you have no history of chronic headaches

Remember, one headache is not a cause for a concern. Only frequent, continuous, and worsening headaches should be evaluated.