Dec 19, 2011

Brain Cancer

Brain Cancer.
Brain cancer could be fatal. When our brain is damaged, we will rely on nothing. That is why brain cancer might be categorized the worst and the deadliest disease.

There are two types of brain tumors: primary brain tumors that originate in the brain and metastatic (secondary) brain tumors that originate from cancer cells that have migrated from other parts of the body.
Primary brain cancer rarely spreads beyond the central nervous system, and death result from uncontrolled tumor growth within the limited space of the skull. Metastatic brain cancer indicates advanced disease and has a poor prognosis.

Primary brain tumors can be cancerous or noncancerous. Both types take up space in the brain and may cause serious symptoms (e.g., vision or hearing loss) and complications (e.g., stroke).
All cancerous brain tumors are life threatening (malignant) because they have an aggressive and invasive nature. A noncancerous primary brain tumor is life threatening when it compromises vital structures (e.g., an artery).

In the United States, the annual incidence of brain cancer generally is 15-20 cases per 100,000 people. Brain cancer is the leading cause of cancer-related death in patients younger than age 35.
Primary brain tumors account for 50% of intracranial tumors and secondary brain cancer accounts for the remaining cases. Approximately 17,000 people in the United States are diagnosed with pri¬mary cancer each year and nearly 13,000 die of the disease. The annual incidence of primary brain cancer in children is about 3 per 100,000.

Secondary brain cancer occurs in 20-30% of patients with metastatic disease and incidence increases with age. In the United States, about 100,000 cases of secondary brain cancer are diagnosed each year.

A brain tumor can obstruct the flow of cerebrosinal fluid (CSF), which results in the accumulation of CSF (hydrocephalus) and increased intracranial pressure (IICP). Nausea, vomiting, and headaches are common symptoms.
Brain tumors can damage vital neurological pathways and invade and compress brain tissue. Symptoms usually develop over time and their characteristics depend on the location and size of the tumor. A brain tumor in the frontal lobe may cause the following:
  • Behavioral and emotional changes
  • Impaired judgment
  • Impaired sense of smell
  • Memory loss
  • Paralyses on one side of the body (hemiplegia)
  • Reduced mental capacity (cognitive function)
  • Vision loss and inflammation of the optic nerve (papilledema)
 A tumor located in both the right and left hemispheres of the frontal lobe often cause behavioral changes, cognitive changes, and a clumsy, uncoordinated gait.
A tumor in the parietal lobe may cause the following symptoms:
  • Impaired speech
  • Inability to write
  • Lack of recognition
  • Seizures
  • Spatial disorders
Vision loss in one or both eyes and seizures may result from a tumor located in the occipital lobe.
Tumors that develop in the temporal lobe are often asymptomatic (i.e. with-out symptoms), but some may cause impaired speech and seizures.

A tumor in the brainstem may produce the following symptoms:
  • Behavioral and emotional changes (e.g., irritability) ,
  • Difficulty speaking and swallowing
  • Drowsiness
  • Headache, especially in the morning,
  • Hearing loss
  • Muscle weakness on one side of the face (e.g., head tilt, crooked smile)
  • Muscle weakness on one side of the body (i.e., hemiparesis)
  • Uncoordinated gait
  • Vision loss, drooping eyelid (i.e., ptosis) or crossed eyes (i.e., strabismus)
  • Vomiting
Ependymoma originates in the lining of the ventricles and the spinal canal and may damage cranial nerves. When this happens, hydrocephalus, stiff neck, head tilt, and weakness may result.
Symptoms produced by a tumor of the meninges (meningioma) depend on which area of the brain is being compressed. They include:
  • Headache
  • Hearing loss
  • Impaired speech (i.e., dysphasia)
  • Incontinence
  • Mental and emotional changes (e.g., indifference, disinhibition)
  • Prolonged drowsiness (somnolence)
  • Seizures
  • Vision loss
A tumor located in the pituitary gland (i.e., pituitary adenoma) may increase the secretion of hormones and cause discontinuation of menstruation (i.e., amenorrhea) and excess secretion of milk (i.e., galactorrhea) in women. Impotence may occur in men.
Metastatic brain cancer tends to invade the brain tissue indiscriminately. Some symptoms include the following:
  • Bleeding
  • Headache
  • Impaired mental function
  • Motor dysfunction
  • Nausea
  • Seizures
  • Swelling
  • Vomiting
Complications drastic and sometimes life-threatening complications can develop with brain cancer.


What is Brain Cancer?
The brain, like any other tissue in the body, is made up of individual cells which are much smaller than a pinpoint, and require a microscope to see them. These cells are the smallest units which compose the brain, and there are several different types. A brain cancer can arise from any of the cells which make up the brain. Basically, the brain's thinking cells (called “neurons”) are meant to divide rapidly before birth, and up until about 7 years old. At this time the brain u fully grown, and contains all the "neurons "that it ever will. Further development is by the existing cells making increasingly elaborate connections with each other, to communicate with one another.

Once the brain cells stop dividing in childhood, they are never meant to divide again. If the brain is injured, such as by trauma or stroke, specific cells within the brain (the “glial cells”) divide to form scar tissue, but the brain's thinking cells (the neurons) don't reproduce (although damaged ones may be repaired). You can see that the division of brain cells is under strict regulation and control. When this control is lost in a single cell, then it starts dividing in an uncontrolled manner. 

Brain cancer starts in just one cell. As the cell makes more and more copies of itself, it grows to form a tumor (which means a swelling). A benign tumor stays where it starts, although it can grow very large and press on crucial areas. In con-trast, a malignant tumor has a capacity to spread, and is then called “brain cancer”. “Primary” brain cancer starts within the brain, and is then main subject of this transcript. In contrast, "secondary" brain cancer starts in some other organ (like lung or breast) and thenspreads to the brain. This is called “brain metastasis”.

Like any cancer, the exact reason why one person gets brain cancer and another doesn't is unknown. However, several things have been found to increase the risk of developing brain cancer:
1) Having rare family diseases, carried in the genes, such as Neurofibromatosis (the “Elephant Man” syndrome), Von-Hippel Lindau, Sturge-Weber's or Turcot’s syndrome. These all belong to a family of diseases called the “phacomacoses” and present with cysts or bumps on or inside the body and high risk for brain tumors.
2) Exposure to certain chemicals, including chlorinated hydrocarbons (like PVC) and benzene, is associated with a higher risk of brain cancers.
3) Exposure to radiation has also been connected to developing brain cancers as well as other malignancies. The risk is greater if the person is exposed to at a young age to a higher dose. Pre-existing benign type tumors may become cancer¬ous (called "malignant degeneration) if radiated.

This depends upon where in the brain the cancer arises, and how big it becomes before coming to medical attention. The brain has particular areas controlling thought, sight, hearing, sensation, move¬ment, coordination and mood. The upper brain area tends to control the more advanced thought functions, while the middle controls mood and movement and the rear (or “brain stem”) stimulates breathing and heart rate.

There are about 15,000 cases per year in the United States of “primary brain cancer”. This causes about 10,000 deaths per year. Thus primary brain cancers account for 2% of the cancers yearly in the U.S.A. Much more common is brain Metastasis with at least 80,000 cases per year in the U.S.A. Since many cancers spread to the brain, and it is a critical structure, this accounts for almost 20% of total cancer deaths each year. While primary brain tumors account for 20% of the cancers in children, the majority of cases are in older individuals.

A tumor simply means a swelling, and isn't necessarily cancer. A patient will come to the doctor with symptoms suspicious for a brain tumor, and the physician will perform a neurological examination to check the nerves or the brain which control the eyes and face, check for equal strength and sensation on both sides of the body, coordination and balance, and memory and judgment. He will look into the eyes for signs of increased pressure in the skull, such as swelling of the optic disks.

The next step is to order a radiological test to look for the tumor. Most commonly a CAT scan is gotten which an array of X-ray beams to visualize the brain. Often contrast material is injected into a vein during the CAT scan, as this highlight abnormal area in the brain. This test takes about 1/2 hour and the films are read by a radiologist. Large tumors are very easily seen on CAT scan, but ones smaller than 1 cm or in the cerebellum may not be obvious.

If a tumor is seen, or there is still high suspicion of one, the next test ordered is a Magnetic Resonance Image (MRI) scan; it doesn't use radiation and is very accurate for detecting even small brain tumors in the cerebellum. It takes about an hour of lying still, is painless, and is much more expensive than a CAT scan, which is why they only order it after confirming a tumor.

The only way to be absolutely sure of what kind of tumor is present is to take a sample (biopsy) of it. Nowadays, biopsies are very safe (less than 1% of patients die from them) and are usually obtained under stereotactic guidance (a fine-needle is exactly placed into the tumor after visualizing it in 3 dimensions). The biopsy material is examined by a pathologist, a doctor who specializes in diagnosing disease from tissue samples. He does special stains on it and examines it under a microscope to see what type of tumor it is, and grades it depending upon how aggressive it looks. Rarely, the type of tumor is so obvious from the scans or is so deep in the brain that a biopsy isn't gotten, the tumor is treated based upon what’s it's presumed to be. 

Other possible tests include an MRI-of the spine for certain tumors (medulloblastoma and high grade ependymoma) which tend to seed down the spine, a spinal tap to look for cancer cells shedding into the cerebral-spinal fluid that bathes the brain, and spinal cord, and an endocrine (hormonal) blood test evaluation for pituitary or mid-brain tumors. We may test to look for the origin of the tumor elsewhere in the body if it is believed not to have started in the brain. Spread of primary brain tumors to other body organs is very rare, but when it occurs it's usually to lung or bone marrow.

Historically, treatment of brain tumors has used surgery, radiation treatment and/or chemotherapy. Each of these has improved dramatically over the past decades. It is critical for the patient to get the correct treatment for brain cancer, the first time. This is because treatment of relapsed cancer isn't as successful as proper initial treatment when the diagnosis is first made. Nonetheless, newer techniques of pinpoint-accuracy radiation, microsurgery, chemotherapy and gene therapy offer more hope to the patient with brain cancer than ever before.
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