Brain Tumors
by F. Stavridi, M.D., Medical Oncologist

Introduction

A brain tumor is a tumor (defined as an abnormal growth of cells) within the brain. There are also tumors in the central spinal canal.

Tumors can be benign or malignant. Benign brain tumors remain in the part of the brain where they started, and do not spread to other areas of the brain

Malignant brain tumors can be either primary or secondary.

  1. A primary tumor is a tumor that starts in the brain.  Malignant primary brain tumors usually cause problems by spreading into the normal brain tissue or around them, causing pressure and damage to other areas of the brain. These tumors rarely spread outside the brain to other parts of the body.
  2. A secondary brain tumor has spread to the brain from somewhere else in the body.

 

Central Nervous System structure

The main parts of the brain that could be affected are the cerebrum, the cerebellum and the brain stem. The brain is contained within the skull, which protects it. Between the brain and the skull there are three layers of membrane called the meninges, which completely cover the brain and spinal cord and help to protect them. The space between two of these layers is called the subarachnoid space, and contains a fluid called "cerebrospinal fluid".

 

Etiology

  • The cause of most primary brain tumors is unknown. Although genes do not seem responsible for causing brain tumors, a small number could occur in people having certain genetic conditions like Li-Fraumeni, Von Hippel-Lindau, or neurofibromatosis.
  • Previous exposure to radiotherapy could predispose a patient to develop a brain tumor.
  • Other factors, such as mobile phones, have been suggested as possible causes of brain tumors, without any proven evidence to date.

 

Symptoms

Patients with brain tumors could have symptoms for two main reasons:

  1. Tumor growing within a limited space of the skull increases the pressure against the normal brain tissue.
  2. Pressure on a certain part of the brain which serves special functions, e.g. memory, vision etc.

Therefore, the most common symptoms are:

  • Headaches (migraines): they can be constant, getting worse by cough or physical exercise. However, severe headaches are rarely correlated with brain tumors.
  • Feeling or actually getting sick (nausea and vomiting): These symptoms are usually worse in the morning, or worsen when the body’s position changes.
  • Drowsiness: Patients usually find themselves sleepier than before.
  • Fits (seizures): they are a rather rare symptom which can be quite frightening. People may either experience jerking of an arm or leg, or both, or even whole body twitching. However, it is important to remember that conditions other than brain tumors could also cause fits.

Other symptoms that could occur are loss of balance, confusion or even personality changes. Medical attention is required if a patient develops any of those symptoms and they are not resolved within ten days.

Some symptoms may be caused by tumors growing in particular parts of the brain interrupting normal brain function, including:

  • Frontal lobe: shifts in personality; lack of coordination when walking, or weakness felt on one side of the body; loss of smell; occasional difficulties during speaking.
  • Parietal lobe: difficulties during speaking and understanding words, writing and reading; difficulties in coordinating certain movements; difficulty in orientation; weakness felt on one side of the body.
  • Temporal lobe: fits (seizures); difficulties during speaking; memory problems.
  • Cerebellum: lack of coordination; slurred speech (dysarthia), loss of stability control.
  • Occipital lobe: loss of vision.

 

Diagnosis & Staging

If a brain tumor is suspected, the primary care physician should refer the patient to:

  • a neurologist or neurosurgeon (a specialist in brain and nerve disorders), or
  • an oncologist (a doctor specialized in cancer treatment).

The specialist doctor will take the patient’s medical history, perform a clinical examination as well as certain tests like brain MRI (Magnetic resonance imaging), CT (Computerized Tomography) or SPECT (single photon emission computerized tomography) scan, in order to get a detailed image of the brain.

Usually a biopsy is required (i.e. removal of a small part of the tumor) in order to find out the exact type of brain tumor. Pathologists (doctors who are specialized in examining cells) can identify the type of cells present, and therefore the type of brain tumor.

 

Pathology

There are many different types of brain tumors that involve different prognosis and treatment strategies.

Types of brain tumors include astrocytoma, acoustic neuroma, haemangioblastoma, medulloblastoma, ependymoma, meningioma, oligodedroglioma, glioblastoma, lymphoma and tumors of the pituitary and pineal region.

An oncologist will inform the patient further on the exact type of brain tumor. Lately, a number of molecular tests are ordered (EGFR, IDH1, MGMT) that are performed on the tumor tissue and can provide information regarding the behavior of the tumor, possible therapeutic targets as well as tumor’s responsiveness to treatment.

 

Treatment

The decision upon the best possible treatment engages a broad team of physicians (including neurosurgeons, medical oncologists, radiotherapists, and neurologists).

Surgery is often the first treatment of primary brain tumors, if the tumor can be removed safely. Nevertheless, certain tumors may not need to be operated on immediately, or even at all.

Radiotherapy is often used after surgery, if a tumor has not been completely removed, or if there is a chance that cancerous cells may be left behind after surgery. When surgery is not possible or not needed, radiotherapy (with or without chemotherapy) is used as the main treatment.

Radiotherapy is often given in parallel with chemotherapy, usually with Temozolamide.

 

Surgical treatment

An operation under general anesthesia can be done to remove the tumor through craniotomy (an operation that involves opening the skull). Some hair may need to be shaved off before the operation. The neurosurgeon will cut the scalp and the piece of skull over the tumor. Sometimes it is impossible to remove the whole tumor, and therefore a partial resection (or debulking) is performed.

There are cases where a healthy part of the brain may be damaged during the surgery, and the likelihood and effect on the patient must be explained before the operation. It will be necessary for the patient to stay in hospital for a few days after the surgery, under very careful monitoring with blood and imaging tests. The patient may have a mild headache upon waking up after the operation, but the symptoms usually settle after the operation.

 

Radiotherapy Treatment

If the brain tumor cannot be removed surgically, radiotherapy may be the main treatment. It may also be administered if any cancer cells have been left behind, or if the tumor has come back after surgery. Patients are treated in short daily sessions for a number of weeks, as determined by the radiotherapists. Sometimes, chemotherapy tablets are provided in parallel to radiation therapy.

For radiotherapy a CT (Computerized Tomography) scan or x-rays of the area to be treated will be needed. In order to show where the rays will be directed and help body placement, marks are usually drawn on the radiotherapy mask.

Side effects of radiotherapy depend on the amount of radiation administered, and the length of treatment. Radiotherapy can cause headaches, sickness, tiredness, drowsiness, mild skin changes and hair loss. There are medications that can be used to minimize those side effects (e.g. painkillers, steroids, anti-sickness medication etc).

Long-term side effects are rare nowadays, mainly because of advanced technologies used during radiation therapy, and may include changes of the memory, inability to think clearly, and visual loss.

 

Chemotherapy

Chemotherapy might be used for patients with high-grade primary brain tumors, either as an initial treatment alongside radiotherapy, or in case the tumor has come back.

The main chemotherapy drugs used to treat primary brain tumors include temozolomide,carmustine, procarbazine, lomustine and vincristine, given either as tablets or by injection into a vein (intravenously). Sometimes lomustine, procarbazine and vincristine are used together in combination (such combination is called PCV). Recent studies have incorporated biological agents like bevacizumab in the treatment of glioblastoma.

Chemotherapy can cause side effects including lowered resistance to infection from low white blood cells, low number of red blood cells, bruising and bleeding because of low number of platelets, feeling sick and vomiting, hair loss|, as well as tiredness. Although the severity of symptoms differs from patient to patient, some people can lead a fairly normal life during their treatment.

 

Supportive treatment

Steroids are drugs used to reduce the swelling that often surrounds brain tumors, thus improve symptoms and make patients comfortable. They may be used before or after surgery, or during or after radiotherapy. Taking steroids could cause temporary side effects as weight gain, raised blood sugar, mood changes, indigestion, muscle weakness, raised blood pressure and a slightly greater risk of infections. These are only temporary and they gradually disappear as the steroid dose is lowered. The dosage must be controlled in collaboration with the specialist doctor, and stopping steroid use must be gradual and not sudden.

Finally, seizures or fits before surgery may require anticonvulsant drugs. There are many different types of such drugs, like carbamazepine, lamotrigine, levetiracetam, phenytoin etc.

 

Follow up

Once treatment is completed, follow-up through regular check-ups and MRI scans may span several years, perhaps becoming less frequent as time goes on. Healthy diet, regular exercise, giving up smoking, and emotional wellness could help adjustment to life after cancer diagnosis.

 

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