“Ask Dr. HKSH” - Brain Tumours at A Glance
Q1. What is a brain tumour? How is it categorised?
Brain tumours refer to the growth of abnormal cells in the brain. They can be benign or malignant: the former tend to grow at a slower rate than the latter. While benign tumours usually stay in one place, malignant tumours may move with the cerebrospinal fluid and spread to the other parts of the brain, even the connecting cervical vertebrae.
By cell origin, brain tumours can also be categorised as primary or metastatic. The most common type of primary brain tumour is glioma. Some of them are very aggressive, some less so. Among the very aggressive ones, globlastoma multiforme is the most common. Other gliomas include oligodendroglioma and astrocytoma.
Meningioma and other relatively benign tumours such as acoustic neuroma are also primary tumours. There are secondary or metastatic tumours. They originate from other parts of the body except the brain, and reach the brain through the bloodstream. Metastatic tumours are most common in lung cancer, breast cancer, etc.
Q2. What are the symptoms of brain tumours?
The symptoms of brain tumours vary with size, location and lesion number. Intracranial pressure increases with tumour size, and the larger the pressure, the poorer the condition. A brain tumour will affect vision if it grows near the optic centre, or cause such symptoms as limb weakness if located in the motor cortex. A variety of symptoms may occur in case of multiple tumours.
Brain tumours may also lead to hydrocephalus. Symptoms may worsen if inflammation occurs in the periphery of tumours and causes edema. A brain tumour in the ventricle may affect the circulation and discharge of cerebrospinal fluid, causing hydrocephalus with symptoms such as headache, epilepsy or nausea.
Q3. How are brain tumours being diagnosed?
Imaging modalities such as computed tomography (CT),magnetic resonance imaging (MRI), etc. are mostly used in brain tumour diagnosis. In case of secondary or metastatic tumours, whole body scanning such as positron emission tomography/computed tomography (PET/CT) is performed to detect the tumour origin. Biopsy or pathological examination is also conducted. To confirm tumour characteristics, neurosurgeons will perform a local brain tissue biopsy when necessary.
Q4. What are the treatments for brain tumours?
There are three types of brain tumour treatment, namely surgery, radiotherapy and medication. Each can be carried out alone or in combination with others, depending on tumour pathology. Conventional surgery like craniotomy can be performed more precisely with brain mapping for functional measurement, ultrasound or other imaging methods during surgery. Small tumours can be treated by minimally invasive surgery to reduce complications.
The mainstay of radiotherapy for brain tumours are photon therapy and proton therapy. By duration of treatment, radiotherapy can be categorised as conventionally fractionated radiotherapy and stereotactic body radiation therapy (SBRT), the latter of which uses high dose and requires fewer treatments. Generally speaking, benign tumours are less invasive. With SBRT, high-dose radiation can be delivered directly to the tumour site once or several times with high precision. Patients with malignant tumours or irregular large mass may need conventionally fractionated radiotherapy with longer treatment duration, usually up to 5 or 6 weeks.
The choice of medication for treating brain tumour is limited. Oral chemotherapy drugs such as Temodal is usually prescribed for treating globlastoma multiforme, while Carboplatin injections may be administered to children with brain tumours.
Q5. What are the treatment side effects?
The side effects differ from treatment to treatment. In surgery, surgeons will try their best to remove tumours with minimal harm to patients. While highly invasive tumours may not be removed completely by surgery, the residual parts can be treated by radiotherapy and pharmacological means.
By comparison, patients suffer less severe side effects and discomfort after 5 to 6 weeks of radiotherapy, e.g. tiredness, headache, loss of appetite. It can cause vomiting if the cerebral edema or hydrocephalus worsens during treatment. Doctors will look into all possible causes based on the patients’ condition. If the symptoms are mild, steroids may be prescribed to alleviate treatment-related edema.
As a major side effect of chemotherapy, bone marrow suppression can result in lower immunity after treatment. Other possible side effects include hair loss and bowel discomfort, such as vomiting, etc.
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