What are brain tumours?
A brain tumour is an abnormal growth of cells within the brain. It arises from glial cells of the brain, lymphatic tissues, nerves and meninges. Benign brain tumours grow slowly but they can compress adjacent parts of the brain. Malignant tumours grow rapidly and they invade adjacent structures of the brain. Brain tumours are graded according to the nature of cell growth. Grade I and II tumours are grouped as low-grade, whereas grade III and IV are grouped as high-grade tumours. Prognosis is better in low-grade or benign tumours.
The following types of brain tumours are seen commonly:
In children: Juvenile pilocytic astrocytoma, craniopharyngioma, medulloblastoma, brainstem glioma and germ cell tumours.
In adults: Astrocytoma, oligodendroglioma, ependymoma, meningioma, vestibular schwannoma and lymphoma. Cancers from other parts of the body can also spread to brain.
What are the common symptoms of brain tumours?
* Headaches, usually in the morning
* Convulsions or seizures
* Weakness in limbs
* Loss of balance while walking
* Altered speech or vision
* Altered behaviour
* Loss of orientation
* Memory lapses
How are brain tumours diagnosed?
* Imaging: CT scan or MRI scan of brain is commonly performed.
* Biopsy: A piece of tumour is removed for examination by open surgery or in stereotactic fashion using rigid frame to fix skull and localizing tumour under guidance of CT scan or MRI.
Brain tumours are treated by surgery, radiation therapy or chemotherapy, or a combination of these. The choice of treatment depends upon the age of the patient, type of tumour, its location, size and grade.
* Surgery: Maximum safe resection of the tumour or at least a biopsy is the standard goal of surgery.
* Radiation therapy: Radiation kills tumour cells with high energy X-rays, gamma rays or protons. It is usually started after surgery and given over 5-6 weeks.
* Chemotherapy: Chemotherapy is the use of drugs to kill cancer cells. It is given orally or through veins. It is given concomitantly with radiation therapy in high-grade tumours. It is also given in recurrent brain tumours after failure of initial treatment.
What are the advances in radiation therapy of brain tumours?
* 3-Dimensional Conformal Radiation Therapy (3D-CRT) and Intensity Modulated Radiation Therapy (IMRT):
CT scan and MRI are used to delineate the tumour and computers are used for radiation planning. Only the tumour and the high-risk region surrounding the tumour is radiated, avoiding radiation to the normal structures in the brain.
* Stereotactic Radio-surgery (SRS) and Stereotactic Radiotherapy (SRT): Highly precise immobilization and image guidance system is used for treatment of selected brain tumours. High dose of radiation is delivered only to the tumour with very minimal spillage of dose to the rest of the sensitive brain structures. Stereotactic radiotherapy is preferred in children. Stereotactic radio-surgery delivering high-dose of radiation in single or a very few sessions is performed in adults with tumours such as metastatic residual glioma, meningioma and schwannoma. Novalis-Tx and Cyberknife are advanced machines to deliver such high-precision therapy.
* High-definition Rapid Arc: This is the latest software advancement in radiation planning technology. Radiation is delivered in continuous fashion moving the machine head and its small components simultaneously around the patient’s head targeting the tumour by infinite small radiation beams. Radiation treatment with such a technique is highly precise and fast. This is preferred in children and elderly patients who cannot lie on treatment couches for long periods.
* Proton beam therapy: Proton therapy avoids spillage of radiation dose to the surrounding brain. It is preferred in children as well as in patients with recurrent tumours who have received radiation therapy earlier.