Brain cancer at a glance
- Brain cancer is the result of brain cells growing abnormally to form a cancerous brain tumor.
- There are many types of cancerous brain tumors, and each primary brain tumor is categorized based on the type of normal brain cell from which they originated.
- Scientists have researched brain cancer for decades in search of possible causes, identifying a number of factors but no certain cause.
- Symptoms of brain cancer can be hidden for long periods and extremely varied once they do appear.
- Treatment varies depending on the patient and type of tumor. However, brain cancer treatment typically includes several kinds of therapies, including surgery, chemotherapy, traditional radiation and radiosurgery
- About 13,000 people die from cancerous brain tumors each year. Survival rates vary widely depending upon the type of brain tumor, severity, and the general health and age of the patient.
What is brain cancer?
Brain cancer is the uncontrollable growth of abnormal cells in the brain, culminating into a collection of cells called a brain tumor. Not all brain tumors are cancerous, some are benign. Tumors are classified by the types of brain cells they have evolved from. Primary brain tumors, therefore, arise from brain cells that have become malignant. Metastatic brain tumors, on the other hand, occur when abnormal cells originating in another part of the body, such as the lung or breast, are carried to the brain by the blood or other body fluids.
Both primary and metastatic brain tumors are very dangerous because they can compress sensitive brain tissue and nerves within the head, causing patients to experience symptoms such as headaches, nausea, vision loss, hearing loss, pain, seizures or difficulties with balance to just name a few.
As these tumors grow larger, they can be life-threatening because they disrupt critical parts of the brain that are responsible for breathing and other basic life functions.
More than 18,000 cases of primary brain tumors and more than 170,000 brain metastases are diagnosed in the United States each year.
Primary brain tumors
There are many types of primary brain tumors. Each are categorized by their cellular origin and each has its own unique growth patterns and characteristics. Primary brain tumors include:
Benign brain tumors:
- Meningiomas originate from the menginges, the membranes covering the brain and spinal cord.
- Pituitary adenomas occur in the pituitary gland, a pea-size organ located at the base of the brain that helps control growth, blood pressure, certain sexual functions, the thyroid gland and metabolism.
- Schwannomas are tumors that form in the coatings around nerve fibers, which handle messages to and from the brain.
Malignant brain tumors:
- Gliomas are a broad category of tumors in the brain and the spinal cord that originate in glial cells, which are cells that protect and nourish neurons. There are four types of gliomas: astrocytomas, ependymomas, medulloblastomas and oligodendrogliomas. Combined, they account for 40 percent of all primary brain tumors and often spread from the brain to other parts of the body. The most aggressive (and often most fatal) glioma type is glioblastoma multiforme (GBM).
Metastatic brain tumors
Metastatic brain tumors occur when cancer spreads to the brain from other parts of the body through the bloodstream, along nerves or within the fluid surrounding the spinal cord and brain. These cells most commonly originate in tumors within the lung, skin, breast or colon, and are deposited in the brain where they grow into a tumor. A cancer that spreads from its site of origin to a distant site or from one organ to another that it is not connected is called metastatic.
What causes brain cancer?
Doctors and scientists have yet to fully pinpoint a cause for brain cancer. However, cancer researchers today are focusing on genetics in their quest for answers.
All cells in the body are regulated by chromosomes, which are long strands of DNA (deoxyribonucleic acid). In turn, DNA makes up the genes inherited from parents and contain the information needed for cells to grow and function.
Genes control the growth, division and lifespan of cells. Genes involved in cell growth and division are known as oncogenes. Genes that block cell division and that cause the death of cells at the optimum point in time are called tumor suppressor genes.
Cancers can be the result of changes in DNA that activate oncogenes or deactivate tumor suppressor genes. Sometimes the DNA changes are inherited, although in most cases the changes occur over a person’s lifetime.
Risk factors for brain cancer
While researchers continue to investigate the role of DNA in brain cancer, doctors and scientists have also identified and/or investigated certain risk factors, such as:
- Family history – About one in 20 cases of brain tumors are associated with inherited conditions, including those known as Li-Fraumeni syndrome, nevoid basal cell carcinoma syndrome, tuberous sclerosis, von Hippel-Lindau syndrome, Turcot syndrome and neurofibromatosis.
- Age and gender – Brain cancer occurs more often in children and older adults, and men generally get brain cancer more often than women, although some forms are more common in females.
- Certain viruses and infections – Infections with the Epstein-Barr virus (the one that causes mononucleosis) and the cytomegalovirus (which spreads via bodily fluids) have been associated with certain kinds of brain tumors, although researchers are unclear of the strength of the association.
- Race – American Caucasians have a higher incidence of gliomas than African Americans but a lower rate of meningioma. People of northern European descent are more than twice as likely to develop brain tumors as Japanese people.
- Head injuries – Some scientific studies have found an association between meningioma and head trauma but no links between head trauma and glioma.
- Seizures – Many people with seizures have been diagnosed with brain tumors, although doctors don’t know if the tumors are the cause of the seizures, if anti-seizure medication these patients take increases the risk, or if seizures boost the odds of cancer.
- Environmental exposure – Researchers have studied the possible effects that pesticides, solvents, vinyl chloride, rubber and petroleum products may have on brain cancer, although they have yet to find scientific evidence of any links. However, one study of military combat veterans indicated increased risk of tumors from exposure to nerve agents, although more research is needed to establish any link.
Do cell phones cause brain cancer?
There has been much scientific research on this controversial question. The findings thus far are inconsistent.
A study published in late 2014 showed that using a wireless phone for more than 25 years tripled the risk of glioma. The study also found that the risk is greater among people who had started using wireless phones before age 20. Ironically, the study discovered additionally that advancing cell phone technology is actually worsening risks.
Yet another study that followed 420,000 cell phone users over 20 years found no link between cell phones and brain cancer.
Regardless, it typically takes researchers decades to identify a cancer-causing agent, as it took with tobacco research in the last century. In the meantime, common steps for good health include reducing cell phone use, limiting children’s use, using a shielded headset, using cell phones only in areas with the strongest reception.
Symptoms of brain cancer
Symptoms of brain cancer can be elusive. Some tumors cause no symptoms until becoming quite large. In other cases, brain cancer symptoms come on slowly.
Because the brain is the command center for every bodily function, symptoms of brain cancer can vary widely and manifests differently. Symptoms can include:
- Weakness or tremors in one part of the body
- Loss of coordination or balance
- Changes in personality, mood or mental functioning (such as memory and the ability to read and write)
- Changes in speech, such as the ability to find the right words
- Lessening of the ability to feel pain, heat or cold
- Changes in pulse and breathing
- Loss of bladder and/or bowel control
- Difficulty swallowing
- Dizziness and/or vertigo
- Nausea and vomiting
- Vision difficulties, eyelid dropping, uncontrollable eye movement, pupils of different sizes.