Brain Tumors are tumors inside of the skull. They occur when cells start dividing and replicating uncontrollably. Tumors can either originate from the brain tissue itself, the tissues covering the brain, blood vessels, or other structures in or around the brain. Cancer may also spread, or metastasize, to become a brain tumor.
Brain tumors may be benign (not cancer) or malignant (cancer). However, brain cancer rarely, if ever, spreads to other places in the body. This is different from other cancers. Also, unlike other tumors, brain tumors can be more dangerous and life threatening. As the brain tumor grows and occupies more space, it pushes the normal brain to the side. Because the surrounding skull is made of bone, the rest of the brain is compressed and may cause symptoms or even death.
Brain tumors are usually found after they cause neurologic symptoms or incidentally, during brain imaging for other reasons. Common neurologic symptoms are headache, tiredness, confusion, mood or personality changes, nausea, vomiting, visual changes, balance problems, seizures, speech problems, or weakness. Many of these symptoms are similar to those caused by a stroke. The exact symptoms tend to be based on the tumor’s size and its location in the brain. Different areas of the brain have different functions so even the same brain tumor may cause different symptoms in different people. If any of these symptoms arise, you should notify your primary care physician.
Brain tumors account for about one percent of all cancers in the U.S., and just over two percent of all cancer deaths. They can be classified in many ways, based on tissue of origin or even location. The most common brain tumors overall are metastases. The most common tumor that starts from the brain tissue itself is glioblastoma multiforme (GBM). Of course, many other tumor types exist. Tumors from astrocytes, the brain’s supporting cells, may form low-grade astrocytomas or more malignant tumors like anaplastic astrocytomas or GBMs. Tumors from cells that produce myelin, a conductive tissue around the nerves, form oligodendrogliomas or schwannomas. Tumors from the tissue covering the brain form meningiomas. Tumors of the lymphatic system form lymphomas. Numerous other tumors exist, but tend to be rarer in adults. Tumors may also be described by their aggressiveness, or malignancy. The World Health Organization (WHO) devised a grading system from grade I (most benign) to grade IV (most malignant).
In the U.S., three- to-five newly diagnosed cases of GBM occur per 100,000 people per year. Although GBM occurs most frequently in adults older than 60 years, it may present at any age and it can occur nearly anywhere in the brain. The cause is unknown, but it can either arise spontaneously or from a more benign tumor. Risk factors include radiation and genetic predisposition. It is unknown whether occupational exposures, electromagnetic field exposure, or trauma are causes. Currently there is no long-term evidence relating GBMs to cellular phone use.
GBMs are WHO-grade IV tumors, and very malignant. The prognosis is poor with median survival of three months without treatment. Survival with a brain tumor can be described in two ways. Progression-free survival is the time from diagnosis until the cancer gets “worse.” Overall survival is the time from diagnosis until the patient dies from the cancer. With surgery, radiation, and chemotherapy, progression-free survival for GBM averages seven months while overall survival averages 15 months. Newer studies involving highly aggressive treatments in certain patients have shown median overall survival up to 19-22 months.
Surgery is the initial treatment used to treat most brain tumors, including GBM. Unfortunately, GBMs grow in an infiltrative manner so that there rarely is a border between the tumor and normal brain. It therefore is nearly impossible to completely remove the tumor, and surgery focuses on removing only a majority. This commonly relieves many of the patient’s symptoms. Chemotherapy and radiation are then used to treat the remaining tumor. Sometimes when the tumor involves an important part of the brain, only a small biopsy is taken and the tumor is primarily treated with chemotherapy and radiation. Newer surgical tools are now available that help visualize the tumor separate from the normal brain during surgery. This can increase the amount removed and potentially increase survival. Chemotherapy has also improved and can better target certain genetic features of GBMs.
Metastases are the most common type of brain tumor overall, and approximately 25% of patients who die of cancer have brain metastases on autopsy. The most common brain metastases are from lung, breast, skin, and kidney cancers. Surgery for brain metastases is indicated in many different situations. Sometimes the tumors are biopsied and sometimes completely removed, depending on their location, size, and other factors. Patients with brain metastases often are more likely to die from their brain tumor than from the cancer in the rest of their body, so surgery is becoming more common to increase the patient’s remaining quality of life. Chemotherapy and radiation are still necessary following brain surgery. The prognosis and survivorship of brain metastases depends on numerous factors.
If you have a brain tumor and would like to understand your surgical options, please call The Neurosurgery Center of Colorado at 303-481-0035 to make an appointment with Adam P. Smith, MD.
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