Brain Cancer

Tumors in the brain are dangerous because they press on areas of the brain as they grow.

Brain cancer is a disease of the brain in which cancer cells (malignant cells) arise in the brain tissue (cancer of the brain). Cancer cells grow to form a mass of cancer tissue (tumor) that interferes with brain functions such as muscle control, sensation, memory, and other normal body functions.

• Tumors composed of cancer cells are called malignant tumors, and those composed of mainly noncancerous cells are called benign tumors.
• Cancer cells that develop from brain tissue are called primary brain tumors while tumors that spread from other body sites to the brain are termed metastatic or secondary brain tumors.

Statistics suggest that brain cancer occurs infrequently (less than 1% of all new cancer patients per year), so it is not considered to be a common illness and is likely to develop in about 24,810 new people per year with about 18,990 deaths as estimated by the National Cancer Institute (NCI) and the American Cancer Society. Only about 5% of brain tumors may be due to hereditary genetic conditions such as neurofibromatosis, tuberous sclerosis, and a few others.

What is metastatic brain cancer? 

Cancer cells that develop in a body organ such as the lung (primary cancer tissue type) can spread via direct extension, or through the lymphatic system and/or through the bloodstream to other body organs such as the brain. Tumors formed by such cancer cells that spread (metastasize) to other organs are called metastatic tumors.

Metastatic brain cancer is a mass of cells (tumor) that originated in another body organ and has spread into the brain tissue. Metastatic tumors in the brain are more common than primary brain tumors. They are usually named after the tissue or organ where cancer first developed (for example, metastatic lung or breast cancer tumors in the brain, which are the most common types found). Occasionally, an abbreviated name may be used that often confuses people; for example, "small cell brain cancer" actually means "small cell lung cancer that has metastasized to the brain." People should not hesitate to ask their doctor about any terms they do not understand or about the origin of their cancer.

Meningiomas are the primary brain tumors that are the most common. More than 35% of primary brain tumors are meningiomas.

The most common primary brain tumors are usually named for the brain tissue type (including brain stem cancers) from which they originally developed.

• Five brain tumors are gliomas, meningiomas, pituitary adenomas, vestibular schwannomas, and primitive neuroectodermal tumors (medulloblastomas).
  • Gliomas have several subtypes, which include astrocytomas (for example, an astrocytoma is a brain cancer composed of abnormal brain cells known as astrocytes), oligodendrogliomas, ependymomas, and choroid plexus papillomas. Glioblastomas arise from astrocytes and are usually highly aggressive (malignant) tumors.
• These names all reflect different types of cells in the normal brain that can become cancers. When the grades are coupled with the tumor name, it gives doctors a better understanding of the severity of brain cancer. For example, a grade III (anaplastic) glioma is an aggressive tumor, while an acoustic neuroma is a grade I benign tumor.
• However, even benign tumors can cause serious problems if they grow big enough to cause increased intracranial pressure or obstruct vascular structures or cerebrospinal fluid flow.

Primary brain tumors arise from many types of brain tissue (for example, glial cells, astrocytes, and other brain cell types). Metastatic brain cancer is caused by the spread of cancer cells from a body organ to the brain. However, the causes for the change from normal cells to cancer cells in both metastatic and primary brain tumors are not fully understood. Data gathered by research scientists show that people with certain risk factors are more likely to develop brain cancer.

Individuals with risk factors show higher rates of brain cancer than the general population, such as:

• having a job in an oil refinery,
• handlers of jet fuel or chemicals like benzene,
• chemists,
• embalmers, or
• rubber-industry workers.

Some families have several members with brain cancer, but heredity (genetic passage of traits from parents to children) as a cause for brain tumors has not been proven. Other risk factors such as smoking, radiation exposure, and viral infection (HIV) have been suggested but not proven to cause brain cancer.

There is no good evidence that brain cancer is contagious or caused by head trauma.

Many studies have been done to investigate whether the radiation produced from cell phones can be linked to the development of brain cancer or other cancers. To date, there has been no evidence to suggest that cell phone use is linked to the development of brain cancer. The US National Cancer Institute has developed a fact sheet on cell phone use and cancer risk to address these concerns. (https://www.cancer.gov/about-cancer/causes-prevention/risk/radiation/cell-phones-fact-sheet#:~:text=Many%20different%20kinds%20of%20studies,kinds%20of%20cancer%20in%20humans.)

Although there are few early warning signs, the most common signs and symptoms of brain cancer may include one or more of the following:

• Difficulty walking and/or dizziness/vertigo
• Seizures
• Muscle weakness (for example, arm, and leg weakness)
• Headaches (persistent and/or severe)

Other common symptoms that can occur include:

• nausea,
• vomiting,
• blurry vision,
• a change in a person's alertness,
• sleepiness,
• mental capacity reduction and/or confusion,
• memory problems,
• changes in speech, such as difficulty speaking, impaired voice, or inability to speak,
• personality changes,
• hallucinations,
• weakness on one side of the body,
• coordination problems,
• fatigue, and
• pins and needles sensations and/or reduced sensation of touch.

These symptoms can also occur in people who do not have brain cancer, and none of these symptoms alone or in combination can predict that a person has brain cancer. Cancer can occur in any part of the brain (for example, occipital, frontal, parietal, or temporal lobes, brainstem, or meningeal membranes [meninges; the singular is meninx]).

Primary cerebral lymphoma can occur but is rare; so are craniopharyngiomas that are derived from the pituitary gland. A few brain cancers may produce few or no symptoms (for example, some meningeal and pituitary gland tumors).

The initial test is an interview that includes a medical history and physical examination of the person by a healthcare provider. The results of this interaction will determine if other specific tests need to be done.

The most frequently used test to detect brain cancer is a CT scan (computerized tomography). This test resembles a series of X-rays and is not painful, although sometimes a dye needs to be injected into a vein for better images of some internal brain structures. Another test that is gaining popularity because of its high sensitivity for detecting anatomic changes in the brain is MRI (magnetic resonance imaging). This test also shows the brain structures in detail better than CT. If the tests show evidence (tumors or abnormalities in the brain tissue) of brain cancer, then other doctors such as neurosurgeons and neurologists that specialize in treating brain ailments will be consulted to help determine what should be done to treat the patient.

Occasionally, a tissue sample (biopsy) may be obtained by surgery or insertion of a needle to help determine the diagnosis. Other tests (white blood cell counts, electrolytes, or examination of cerebrospinal fluid to detect abnormal cells or increased intracranial pressure) may be ordered by the healthcare practitioner to help determine the patient's state of health or to detect other health problems. These tests help differentiate between cancerous and non-cancerous conditions in the brain that may produce similar symptoms (for example, Hippel-Lindau disease or diseases in the spinal cord or the nervous system outside of the brain).

Brain cancers are staged (stage describes the extent of cancer) according to their cell type and grade because they seldom spread to other organs, while other cancers, such as breast or lung cancer, are staged according to so-called TMN staging which is based on the location and spread of cancer cells. In general, these cancer stages range from 0 to 4; with stage 4 indicating cancer has spread to another organ (the highest stage is 4).

Not all brain tumors are alike, even if they arise from the same type of brain tissue. Tumors are assigned a grade depending on how the cells in the tumor appear microscopically. The grade also provides insight into the cell's growth rate. NCI lists the following grades from benign to most aggressive (grade IV):

1. Grade I: The tissue is benign. The cells look nearly like normal brain cells, and they grow slowly.
2. Grade II: The tissue is malignant. The cells look less like normal cells than do the cells in a grade I tumor.
3. Grade III: The malignant tissue has cells that look very different from normal cells. The abnormal cells are actively growing and have a distinctly abnormal appearance (anaplastic).
4. Grade IV: The malignant tissue has cells that look most abnormal and tend to grow quickly.

A treatment plan is individualized for each brain cancer patient. The treatment plan is constructed by the doctors who specialize in brain cancer, and treatments vary widely depending on the cancer type, brain location, tumor size, patient age, and the patient's general health status. A major part of the plan is also determined by the patient's wishes. Patients should discuss treatment options with their health care providers.

Surgery, radiation therapy, and chemotherapy are the major treatment categories for most brain cancers. Individual treatment plans often include a combination of these treatments.

• Surgical therapy attempts to remove all of the tumor cells by cutting the tumor away from normal brain tissue. This surgery that involves opening the skull (craniotomy) is often termed invasive surgery to distinguish it from noninvasive radiosurgery or radiation therapy described below. Some brain cancers are termed inoperable by surgeons because attempting to remove cancer may cause further brain damage or death. However, a brain cancer termed inoperable by one surgeon may be considered operable by another surgeon. Patients with a diagnosis of an inoperable brain tumor should consider seeking a second opinion before surgical treatment is abandoned.
• Radiation therapy attempts to destroy tumor cells by using high-energy radiation focused on the tumor to destroy the tumor cells' ability to function and replicate. Radiosurgery is a nonsurgical procedure that delivers a single high dose of precisely targeted radiation using highly focused gamma-ray or X-ray beams that converge on the specific area or areas of the brain where the tumor or other abnormality is located, minimizing the amount of radiation to healthy brain tissue. Equipment used to do radiosurgery varies in its radiation source; a gamma knife uses focused gamma rays, and a linear accelerator uses photons, while heavy-charged particle radiosurgery uses a proton beam. Tomotherapy is a type of radiotherapy in which radiation is delivered in a highly precise and individualized manner that minimizes radiation exposure to healthy tissue; it has also been used to treat brain cancer.
• Chemotherapy attempts to destroy tumor cells using chemicals (drugs) that are designed to destroy specific types of cancer cells. There are many chemical agents used; specific drug therapies are numerous, and each regimen is usually designed for the specific type of brain cancer and individualized for each patient. For example, bevacizumab is a drug approved for the treatment of glioblastomas (glioblastoma multiforme). Chemotherapy can be administered intrathecally (into the cerebrospinal fluid by a spinal tap or through a surgically placed permanent reservoir under the scalp attached through a sterile tubing placed into the fluid-containing chambers in the brain), by IV administration, and biodegradable chemically impregnated polymers. All treatments attempt to spare normal brain cells.
• Other treatment options may include hyperthermia (heat treatments), immunotherapy (immune cells directed to kill certain cancer cell types), or steroids to reduce inflammation and brain swelling. These may be added to other treatment plans.
• Clinical trials (treatment plans designed by scientists and physicians to try new chemicals or treatment methods on patients) can be another way for patients to obtain treatment specifically for their cancer cell type. Clinical trials are part of the research efforts to produce better treatments for all disease types. Stem cell treatments for brain and brain stem cancers and other conditions may be available because research with patients is ongoing using these potential therapies. The best treatment for brain cancer is designed by a team of cancer specialists in conjunction with the wishes of the patient.

Side effects of brain cancer treatment vary with the treatment plan (for example, surgery, chemotherapy, or radiation) and the overall health status of the patient. Most treatment plans try to keep all side effects to a minimum. For some patients, the side effects of brain cancer treatment can be severe.

Treatment plans should include a discussion of potential side effects and the likelihood of them developing, so the patient and their caregivers (family and friends) can make appropriate treatment decisions in conjunction with their medical team. Also, if side effects develop, the patient has some knowledge of what to do about them such as when to take certain medicines (for example, anti-nausea medication is frequently given) or when to call their doctor to report health changes.

Surgical side effects include:

• an increase in current symptoms,
• damage to normal brain tissue,
• brain swelling, and
• seizures.

Other symptoms of changes in brain function such as muscle weakness, mental changes, and decreases in any brain-controlled function can occur. Combinations of these side effects may happen. The side effects are most noticeable shortly after surgery but frequently decline over time. Occasionally, the side effects do not go away.

Chemotherapy usually affects (damages or kills) rapidly growing cancer cells but also can affect normal tissue. Chemotherapy is usually given intravenously so the drugs can reach most body organs.

Common side effects of chemotherapy are:

• nausea,
• vomiting,
• hair loss, and
• loss of energy.

The immune system is often depressed by chemotherapy, which results in a high susceptibility to infections. Other systems, such as the kidneys and the reproductive organs, may also be damaged by chemotherapy and are complications of therapy. Most of the side effects decline over time, but some may not.

Radiation therapy has most of the same side effects as chemotherapy. Most radiation therapy is focused on the brain cancer tissue, so some systems do not receive direct radiation (immune system, kidneys, and others). The effects on systems not receiving direct radiation are usually not as severe as those seen with chemotherapy. However, hair and skin are usually affected, resulting in hair loss (sometimes permanently) and reddish and darkened skin that needs protection from the sun.

Survival of treated brain cancer varies with the cancer type (low-grade versus aggressive and/or inoperable, for example), location, overall age, and general health of the patient. In general, most treatment plans seldom result in a cure. Reports of survival rate or life expectancy greater than five years (which is considered to be long-term survival) vary from less than about 5% to a high of 86%, no matter what treatment plan is used; recovery (cure) from brain cancer is possible, but realistically, complete recovery does not occur often. However, about 75% of children will survive pediatric brain cancer longer than five years; often because of chronic diseases, the elderly have poorer outcomes except with the lowest grade tumors.

So, why use any treatment plan? Without treatment, brain cancers are usually aggressive and result in death within a short period. Treatment plans can prolong survival and can improve the patient's quality of life for some time. Again, the patient and caregivers should discuss the prognosis when deciding on treatment plans.

In general, life expectancy in patients with brain cancer is usually described as a survival rate of five years after diagnosis. The survival rate is expressed as a percentage of people still alive five years after the diagnosis and/or treatment. The survival rates vary with the type and grade of brain cancer and the age of the patient. For example, glioblastomas in patients aged 20-44 have a five-year survival rate of 19% and only a 5% rate in patients aged 55-64. In contrast, patients with meningioma (a benign brain tumor) in the same age groups have survival rates of 87% and 71%, respectively. These survival rates change as advancements in treatment plans improve; the patient and his/her doctors should discuss these rates as they are only estimates, and each person is different. Survival with no reoccurrence of the disease after five years is considered a cure by some; however, close follow-up with doctors is usually recommended to quickly evaluate any possible recurrence of cancer.

Discuss your concerns openly with your doctors and family members. It is common for brain cancer patients to be concerned about how they can continue to lead their lives as normally as possible; it is also common for them to become anxious, depressed, and angry. Most people cope better when they discuss their concerns and feelings.

Although some patients can do this with friends and relatives, others find solace in support groups (people who have brain cancer and are willing to discuss their experiences with other patients) composed of people who have experienced similar situations and feelings. The patient's treatment team of doctors should be able to connect patients with support groups.

In addition, information about local support groups is available from the American Cancer Society at http://www.cancer.org/docroot/home/index.asp or the American Brain Tumor Association at https://www.abta.org/.

Although there is no way to prevent brain cancers, early diagnosis and treatment of tumors that tend to metastasize to the brain may reduce the risk of metastatic brain tumors.

The following factors have been suggested as possible risk factors for primary brain tumors:

• radiation to the head,
• HIV infection, and
• environmental toxins.

However, no one knows the exact causes that initiate brain cancer, especially primary brain cancer, so specific preventive measures are not known. While websites and popular press articles suggest that macrobiotic diets, not using cell phones, and other methods will help prevent brain cancer, there is no reliable data to support these claims.