Thursday, 2 February 2012

Introduction to Brain Tumors

We found this information on a website and found it quite useful in understanding what Sean was going through.

Overview

A tumour (also called a neoplasm or lesion) is abnormal tissue that grows by uncontrolled cell division. Normal cells grow in a controlled manner as new cells replace old or damaged ones. For reasons not fully understood, tumour cells reproduce uncontrollably.

Brain tumours are named after the cell type from which they grow. They may be primary (starting in the brain) or secondary (spreading to the brain from another area). Treatment options vary depending on the tumour type, size and location; whether the tumour has spread; and the age and medical health of the person. Treatment options may be curative or focus on relieving symptoms. Of the more than 120 types of brain tumour's, many can be successfully treated. New therapies are improving the life span and quality of life for many people.

What is a brain tumour?

A primary brain tumour is an abnormal growth that starts in the brain and usually does not spread to other parts of the body. Primary brain tumour's may be benign or malignant.
A benign brain tumour grows slowly, has distinct boundaries, and rarely spreads. Although its cells are not malignant, this tumour composed of benign cells and located in vital areas can be considered life-threatening.

A malignant brain tumour grows quickly, has irregular boundaries, and spreads to nearby brain areas. Although they are sometimes called brain cancer, malignant brain tumour's do not fit the definition of cancer because they do not spread to organs outside the brain and spinal cord.
Metastatic (secondary) brain tumour's begin as cancer elsewhere in the body and spread to the brain. They form when cancer cells are carried in the blood stream to the brain. The most common cancers that spread to the brain are lung and breast.Whether a brain tumour is benign, malignant, or metastatic, all are potentially life-threatening. Enclosed within the bony skull, the brain cannot expand to make room for a growing mass. As a result, the tumour compresses and displaces normal brain tissue (Fig. 1). Some brain tumour's cause a blockage of cerebrospinal fluid (CSF) that flows around and through the brain. This blockage increases intracranial pressure and can enlarge the ventricles (hydrocephalus). Some brain tumours cause swelling (oedema). Size, pressure, and swelling all create "mass effect," which cause many of the symptoms.
tumor mass effect
Figure 1. Brain tumour's compress and displace normal brain tissue.
Increasing size, pressure and swelling cause neurologic symptoms.

Types of brain tumour's

There are over 120 different types of brain tumours. Common brain tumours include:Gliomas
  • Astrocytoma
  • Pilocytic Astrocytoma (grade I)
  • Diffuse Astrocytoma (grade II)
  • Anaplastic Astrocytoma (grade III)
  • Glioblastoma Multiforme (grade IV)
  • Oligodendroglioma (grade II)
  • Anaplastic Oligodendroglioma (grade III)
  • Ependymoma (grade II)
  • Anaplastic Ependymoma (grade III)
Craniopharyngioma
Epidermoid
Lymphoma
Meningioma
Schwannoma (neuroma)
Pituitary adenoma
Pinealoma (pineocytoma, pineoblastoma)
Medulloblastoma
The World Health Organization (WHO) developed a classification and grading system to standardise communication, treatment planning, and predict outcomes for brain tumour's. Tumours are classified by their cell type and grade by viewing the cells, usually taken during a biopsy, under a microscope.
Cell type. Refers to the cell of origin of the tumour. For example, nerve cells (neurons) and support cells (glial and schwann cells) give rise to tumour's. About half of all primary brain tumour's grow from glial cells (gliomas). There are many types of gliomas because there are different kinds of glial cells.Grade. Refers to the way tumour cells look under the microscope and is an indication of aggressiveness (e.g., low grade means least aggressive and high grade means most aggressive) (Table 1). Tumour's often have a mix of cell grades and can change as they grow. Differentiated and anaplastic are terms used to describe how similar or abnormal the tumour cells appear compared to normal cells.Table 1. Glioma Grading Scale
Grade
Characteristics
I
Slow growing cells
Almost normal appearance
Least malignant
Usually associated with long-term survival
II
Relatively slow growing cells
Slightly abnormal appearance
Can invade nearby tissue
Sometimes recur as a higher grade
III
Actively reproducing abnormal cells
Abnormal appearance
Infiltrate normal tissue
Tend to recur, often as a higher grade
IV
Rapidly reproducing abnormal cells
Very abnormal appearance
Area of dead cells (necrosis) in centre
Form new blood vessels to maintain growth

What causes brain tumour's?

Medical science neither knows what causes brain tumours nor how to prevent primary tumours that start in the brain. People most at risk for brain tumours include those who have:
  • cancer elsewhere in the body
  • prolonged exposure to pesticides, industrial solvents, and other chemicals
  • inherited diseases, such as neurofibromatosis

What are the symptoms?

Tumours can affect the brain by destroying normal tissue, compressing normal tissue, or increasing intracranial pressure. Symptoms vary depending on the tumor’s type, size, and location in the brain (Fig. 2). General symptoms include:
  • headaches that tend to worsen in the morning
  • seizures
  • stumbling, dizziness, difficulty walking
  • speech problems (e.g., difficulty finding the right word)
  • vision problems, abnormal eye movements
  • weakness on one side of the body
  • increased intracranial pressure, which causes drowsiness, headaches, nausea and vomiting, sluggish responses
Figure 2. Brain tumour symptoms are related to the functional areas of the brain, giving doctors clues as to the tumour location.
Specific symptoms include:
  • Frontal lobe tumours may cause behavioral and emotional changes, impaired judgment, impaired sense of smell, memory loss, paralysis on one side of the body, reduced mental abilities, and vision loss.
  • tumours may cause impaired speech, inability to write, lack of recognition, and spatial disorders.
  • Occipital lobe tumours may cause vision loss in one or both eyes.
  • Temporal lobe tumours may cause impaired speech and memory difficulty.
  • Brainstem tumours may cause behavioral and emotional changes, difficulty speaking and swallowing, drowsiness, hearing loss, muscle weakness on one side of the face (e.g., head tilt, crooked smile), muscle weakness on one side of the body, uncoordinated gait, drooping eyelid or double vision, and vomiting.
  • Pituitary gland tumours may cause increased secretion of hormones (Cushing’s Disease, acromegaly), a stop in menstruation, abnormal secretion of milk, and decreased libido.

Who is affected?

The American Brain Tumour Association estimates that about 40,900 people will be diagnosed with a primary brain tumour in the US this year (rate of 14 per 100,000 people). Metastatic (secondary) brain tumours are more common than primary brain tumours by at least 10 to 1, and they occur in 20% to 40% of cancer patients. The exact number of brain metastases is unknown, but it has been estimated that 98,000 to 170,000 new cases are diagnosed in the US each year. Unfortunately, each year about 12,690 people die of brain tumours in the US. Although brain tumours can occur at any age, they are most common in children 3 to 12 years old and in adults 40 to 70 years old.

How is a diagnosis made?

First, the doctor will obtain your personal and family medical history and perform a complete physical examination. In addition to checking your general health, the doctor performs a neurological exam to check mental status and memory, cranial nerve function (sight, hearing, smell, tongue and facial movement), muscle strength, coordination, reflexes, and response to pain. Additional tests may include:
  • Audiometry, a hearing test performed by an audiologist, detects hearing loss due to tumors near the cochlear nerve (e.g., acoustic neuroma).
  • An endocrine evaluation measures hormone levels in your blood or urine to detect abnormal levels caused by pituitary tumours (e.g., Cushing’s Disease).
  • A visual field acuity test is performed by a neuro-ophthalmologist to detect vision loss and missing areas in your field of view.
  • A lumbar puncture (spinal tap) may be performed to examine cerebrospinal fluid for tumour cells, proteins, infection, and blood.

Imaging tests

  • Computed Tomography (CT) scan is a safe, noninvasive test that uses an X-ray beam and a computer to make 2-dimensional images of the brain. Similar to an MRI, it views the brain in slices, layer-by-layer, taking a picture of each slice. A dye (contrast agent) may be injected into your bloodstream. CT is especially useful for viewing changes in bony structures.
  • Magnetic Resonance Imaging (MRI) scan is a noninvasive test that uses a magnetic field and radiofrequency waves to give a detailed view of the soft tissues of the brain. It views the brain 3-dimensionally in slices that can be taken from the side or from the top as a cross-section. A dye (contrast agent) may be injected into your bloodstream. MRI is very useful to evaluate brain lesions and their effects on surrounding brain (Fig. 3).
Figure 3. MRI scans of a benign and malignant brain tumour. Benign tumours have well defined edges and are more easily removed surgically. Malignant tumours have an irregular border that invades normal tissue with finger-like projections making surgical removal more difficult.

Biopsy

In some cases, if a diagnosis cannot be made clearly from the scans, a biopsy may be performed to determine what type of tumour is present. Biopsy is a procedure to remove a small amount of tumour to be examined by a pathologist under a microscope. A biopsy can be taken as part of an open surgical procedure to remove the tumour or as a separate diagnostic procedure, known as a needle biopsy via a small hole drilled in the skull . A hollow needle is guided into the tumour and a tissue sample is removed (Fig. 4). A stereotactic biopsy is like a needle biopsy but is performed with the use of a stereotactic head frame and a computer to precisely locate the tumour and direct the needle. This more complex procedure is used for deep tumours in critical locations.
Figure 4. During a needle biopsy, a hollow cannula is inserted into the tumour.
Small biting instruments remove bits of tumour for the pathologist
to examine and determine the exact tumour cell type.

Who treats brain tumours?

Because there are so many kinds of brain tumours and some are complex to treat, many doctors may be involved in your care. Your team may include a neurosurgeon, oncologist, radiation oncologist, radiologist, neurologist, and neuro-ophthalmologist.

What treatments are available?

Treatment options vary depending on the type, grade, size and location of the tumour; whether it has spread; and your age and general health. The goal of treatment may be curative or focus on relieving symptoms (palliative care). Treatments are often used in combination with one another. The goal is to remove all or as much of the tumour as possible through surgery to minimise the chance of recurrence. Radiation therapy and chemotherapy are used to treat tumours that cannot be removed by surgery alone. For example, surgery may remove the bulk of the tumour and a small amount of residual tumour near a critical structure can later be treated with radiation. ObservationSometimes the best treatment is observation. For example, benign, slow growing tumours that are small and have few symptoms may be observed with routine MRI scans every year until their growth or symptoms necessitate surgery. Observation may be the best option for older patients with other health conditions.MedicationMedications are used to control some of the common side effects of brain tumours.
  • Corticosteroid medications, such as dexamethasone (Decadron), are prescribed to reduce swelling and inflammation around the tumor. Because steroid medications can cause stomach ulcers and gastric reflux, famotidine (Pepcid) or pantoprazole (Protonix) are prescribed to reduce the amount of acid produced in the stomach.
  • Furosemide (Lasix) or mannitol (Osmitrol) may be used to control oedema and intracranial pressure.
  • Anticonvulsant medications are used to prevent or control seizures. The most common ones include phenytoin (Dilantin), valproic acid (Depakote), carbamazepine (Tegretol), and levetiracetam (Keppra).
SurgerySurgery is the treatment of choice for brain tumours that can be reached without causing significant injury to vital parts of the brain (eloquent tissue). Surgery can help to refine the diagnosis, remove as much of the tumour as possible, and release pressure within the skull caused by the tumour. A neurosurgeon performs a craniotomy to open the skull and remove the tumour. Sometimes only part of the tumour is removed if it is near critical areas of the brain. A partial removal can still relieve symptoms. Radiation or chemotherapy may be used on the remaining tumour cells.Improvements in techniques, particularly image-guided surgery, intraoperative MRI/CT, and functional brain mapping have improved the surgeon’s ability to precisely locate the tumour, define the tumor’s borders, avoid injury to vital brain areas, and confirm the amount of tumour removal while in the operating room.RadiationRadiation therapy uses controlled high-energy rays to treat brain tumours. Radiation works by damaging the DNA inside cells making them unable to divide and reproduce. The goal of radiation therapy is to maximise the dose to abnormal cells and minimise exposure to normal cells (Fig. 5). The benefits of radiation are not immediate but occur over time. Aggressive tumours, whose cells divide rapidly, typically respond more quickly to radiation. There are two ways to deliver radiation, external and internal beams.
radiation
Figure 5. The radiation beam is shaped to match the tumour and minimise exposure to normal brain tissue. The coloured rings represent the radiation dose level.
External beam radiation is delivered from outside the body by a machine that aims high-energy rays (x-rays, gamma rays) at the tumour.
  • Stereotactic radiosurgery (SRS) delivers a high dose of radiation during a single session. Although it is called surgery, no incision is made.
  • Fractionated stereotactic radiotherapy (FSR) delivers lower doses of radiation over many visits. Patients return daily over several weeks to receive the complete radiation dose.
  • Whole brain radiotherapy (WBRT) delivers the radiation dose to the entire brain. It is often used to treat multiple brain tumors and metastases.
Internal radiation (brachytherapy) is delivered from inside the body by surgically placing radioactive material (sealed in catheters, seeds, or balloons) directly into the tumour. After the patient undergoes a craniotomy to remove the tumour, the radioactive material is placed inside the tumour cavity. The radiation dose is delivered to the first few millimetres of tissue that surrounded the tumour cavity where malignant cells may still remain. Patients have no risk of radiation injury to other parts of their own body or to others around them because the radiation dose is precisely delivered and short lived. ChemotherapyChemotherapy drugs work by interrupting cell division. However, it affects not only tumour cells but normal cells, thus causing side effects, especially in fast growing cells (e.g., hair, digestive, blood). Treatment is delivered in cycles with rest periods in between to allow the body to rebuild healthy cells. Chemotherapy drugs can be administered orally as a pill, intravenously (IV), or as a wafer placed surgically into the tumour. The drugs most commonly used to treat brain tumours are carmustine (BCNU), lomustine (CCNU), and temozolomide (Temodar). Chemotherapy is also used as a radio-sensitizing agent that increases tumour cell death during radiation therapy. Agents that often work in high-grade gliomas include procarbazine, platinum analogs (cisplatin, carboplatin), the nitrosureas (BCNU, CCNU), and alkylating agents (temozolomide, vincristine). BCNU has been proven effective when applied locally to the tumour bed after the tumour has been removed. By applying it directly to the diseased area of the brain, side effects are limited and the drug has a more beneficial effect. Chemotherapy is not routinely used for benign tumours. Adjunct therapies
  • Immunotherapy or biotherapy activates the immune system (T-cells and antibodies) to destroy cancer cells. Experimental research is exploring ways to prevent or treat cancer through vaccines.
  • Gene therapy uses viruses or other vectors to introduce new genetic material into tumour cells. This experimental therapy can cause tumour cells to die or increase their susceptibility to other cancer therapies.
  • Hyperbaric oxygen uses oxygen at higher than normal levels to promote wound healing and help fight infection. It may also improve the tumor’s responsiveness to radiation and is being studied experimentally. Currently it is being used to help the body naturally remove dead tumour cells and treat radiation necrosis.

Recovery & prevention

Self careYour primary care doctor and oncologist should discuss any home care needs with you and your family. Supportive measures vary according to your symptoms. For example, canes or walkers can help those having trouble walking. A plan of care to address changes in mental status should be adapted to each patient’s needs.Driving privileges may be suspended while taking anticonvulsant medication. As each state has different rules about driving and seizures, discuss this issue with your doctor.It may also be appropriate to discuss advance medical directives (e.g., living will, health care proxy, durable power of attorney) with your family to ensure your medical care and wishes are followed.RehabilitationBecause brain tumours develop in parts of the brain that control movement, speech, vision and thinking, rehabilitation may be a necessary part of recovery. Although the brain can sometimes heal itself after the trauma of treatment, it will take time and patience. A neuropsychologist can help patients evaluate changes caused by their brain tumour and develop a plan for rehabilitation. A neuropsychological evaluation assesses the patent's emotional state, daily behaviour, cognitive (mental) abilities, and personality. Physical therapy, occupational therapy, and speech therapy may be helpful to improve or correct lost functions. RecurrenceHow well a tumour will respond to treatment, remain in remission, or recur after treatment depends on the specific tumour type and location. A recurrent tumour may be a tumour that still persists after treatment, one that grows back some time after treatment destroyed it, or a new tumour that grows in the same place as the original one.When a brain tumour is in remission, the tumour cells have stopped growing or multiplying. Periods of remission vary. In general, benign tumours recur less often than malignant ones. Since it is impossible to predict whether or when a particular tumour may recur, lifelong monitoring with MRI or CT scans is essential for people treated for a brain tumour, even a benign lesion. Follow-up scans may be performed every 3 to 6 months or annually, depending on the type of tumour you had.

Glossary

anaplastic: when cells divide rapidly and bear little or no resemblance to normal cells in appearance or function.

astrocytoma: a tumour arising in the supportive cells (astrocytes) of the brain or spinal cord; most often in the cerebrum.

benign: does not invade nearby tissues or spread; noncancerous.

biopsy: a sample of tissue cells for examination under a microscope to determine the existence or cause of a disease.

brachytherapy:
a type of radiation therapy where capsules containing radioactive substances are surgically implanted into the tumour to deliver radiation; also called internal radiotherapy.

cancer:
generic term for more than 100 different diseases caused by uncontrolled, abnormal growth of cells. Cancer cells can invade and destroy normal tissue, and can travel through the bloodstream and lymphatic system to reach other parts of the body.

chemotherapy: treatment with toxic chemicals (e.g., anticancer drugs).
chondrosarcoma: a rare, malignant bone tumour arising from primitive notochord cells and composed of cartilage.

chordoma: a rare, bone tumour arising from primitive notochord cells; usually occurs at the base of the spine (sacrum) or at the skull base (clivus).
craniopharyngioma: a benign tumour arising from cells located near the pituitary stalk.

differentiation:
refers to how developed cancer cells are in a tumour. Well-differentiated tumour cells resemble normal cells and tend to grow and spread at a slower rate than undifferentiated, which lack the structure and function of normal cells and grow uncontrollably.

oedema: tissue swelling caused by the accumulation of fluid.

ependymoma: a tumour arising from the ependyma cells lining the ventricles of the brain and central canal of the spinal cord.

epidermoid:
a benign, congenital tumour arising from ectodermal cells; also called pearly tumour.
glioma: any tumour arising from glial tissue of the brain, which provides energy, nutrients, and other support for nerve cells in the brain.hydrocephalus: an abnormal build-up of cerebrospinal fluid usually caused by a blockage of the ventricular system of the brain; also called “water on the brain.”immunotherapy: treatment designed to improve or restore the immune system’s ability to fight infection and disease.intracranial pressure (ICP): pressure within the skull. Normal ICP is 20 mm HG.lesion: a general term that refers to any change in tissue, such as tumour, blood, malformation, infection, or scar tissue.

lymphoma: a rare tumour arising from lymph cells; may metastasise to the brain from lymphoma tumour elsewhere in the body.

malignant: having the properties of invasive growth and ability to spread to other areas.

mass effect:
damage to the brain due to the bulk of a tumour, the blockage of fluid, and/or excess accumulation of fluid within the skull.

medulloblastoma: a tumour arising from primitive nerve cells; most often in the cerebellum.

meningioma: a tumour arising from the meninges, the membrane that surrounds the brain and spinal cord.

metastasis: the spreading of malignant cells.

metastatic: cancerous tumour that has spread from its original source through the blood or lymph systems.

oligodendroglioma: a tumour arising from the support cells (oligodendroglia) that produce myelin, the fatty covering around nerve cells.

pituitary adenoma: a tumour arising from cells in the pituitary gland; tumour may be hormone-secreting (prolactin, adrenocorticotropic, growth hormone) or not.

radiation: high-energy rays or particle streams used to treat disease.

schwannoma (also called neuroma): a tumour arising from Schwann cells that produce myelin.

stereotactic: a precise method for locating deep brain structures by the use of 3-dimensional coordinates.

tumour: an abnormal growth of tissue resulting from uncontrolled multiplication of cells and serving no physiological function; can be benign or malignant.



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