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Primary tumours that are formed in the brain are typically categorised into benign and malignant (cancerous) tumours. Malignant tumours grow rapidly and are aggressive on the brain which can spread to other parts. Benign tumours grow slowly and are less aggressive.
Based on the appearance of the tumour under a microscope, the types of brain tumours are graded as below:
- Grade IV: Highly malignant.
- Grade III: Also malignant, but not as aggressive as grade IV
- Grade II: Serious brain-invading tumours. Less aggressive than grade III. Sometimes benign, but probably best considered as borderline malignant
- Grade I: Slow growing, less invasive and curable by surgery
From these grades, medicine has divided brain tumours into curable and non-curable tumours. Grade III and Grade IV tumours are highly aggressive. Post surgery, radiation and chemotherapy is advised. Grade I tumours are often treated only with surgery but in some cases, radiation and chemotherapy may be recommended. Meningiomas can be treated with surgery too; however if they recur, radiation may be advised. Primary central nervous system lymphoma can be treated with multi-drug chemotherapy.
Curable Types of Brain Tumours
There are many types of central nervous system tumours but listed below are the more commonly found tumours that are curable.
Schwannoma, the most benign type of brain tumour, occurs from Schwann cells that produce myelin, which covers the peripheral nerve. Schwannomas account for 8-10% of primary tumours and are most commonly found on the eight cranial nerve. Schwannomas can be cured with surgical removal.
These tumours which are formed from the ependymal cells in the brain and line the cerebro-spinal fluid cavities inside the brain and spinal cord are called Ependymomas. These tumours that account for 2.5% adult tumours are also found in children. This is a curable type of brain tumour, of which the five-year survival ranges from 40-60%. The standard treatment involves resection. Chemotherapy and radiation may be advised.
A vast majority of meningiomas are benign and can be cured with surgical resection. Meningiomas account for almost 25% of primary tumours and increase in occurrence with age. Standard therapy for meningiomas involves resection, fractionated radiation and chemotherapy in case of some patients.
4. Dermoid Cyst
They are formed in the posterior fossa and in the midline of the central nervous system. Associated with a type of dermal sinus (a small connection to the skin), these tumours include skin elements like hair, sweat and oil glands. Tumour is curable with surgical resection.
Astrocytoma, Glioblastoma Multiforme and Oligodendroglioma are the most malignant types of brain tumours. In case of patients suffering from low-grade astrocytoma, the 10-year survival chance is around 50%. Glioblastoma Multiforme is the most malignant type of brain tumour known to medics, which has an average survival of about 14-18 months. Oligodendeoglioma, which accounts for 15-20% of primary tumours, has a slightly better chance of survival than astrocytomas. The reason being, it is known to have a better response to radio or chemotherapy with better overall results.
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