Brain tumours are the second most common malignancy in children, after blood cancers. They can be either benign (non-cancerous) or malignant (cancerous) and account for 20% of all childhood cancers. The brain controls various functions of the body, and different parts of the brain are responsible for different functions. There are centres that control motor activity, sensations, vision, hearing, smell, speech, behaviour, thinking, as well as autonomic functions. Unlike other tissues in the body, brain cells cannot regenerate, which makes managing brain Tumours more challenging. Surgery or radiation may have lasting effects on the surrounding normal parts of the brain, impairing functioning.
Brain tumours can develop in children of any age, including newborns. The exact cause of this condition is not identified. However, certain conditions like neurofibromatosis, tuberous sclerosis, and certain genetic alterations are associated with an increased risk of developing tumours.
The symptoms of brain tumours depend on the site of the tumour and the increase in pressure inside the cranial cavity when the tumour blocks the flow of cerebrospinal fluid. Symptoms of increased pressure inside the brain include severe headaches, which are usually worse in the early morning and accompanied by forceful vomiting. Vomiting does not relieve the headache. It is important to differentiate these headaches from other common conditions like migraines, eye strain, or sinus infections. Migraines and eye strain typically worsen towards the evening and can be relieved by sleep or vomiting. Other common symptoms of brain Tumours include seizures, changes in consciousness, weakness in one part of the body, unsteadiness in standing and walking, double vision, difficulty swallowing, nasal regurgitation of food, and aspiration.
In infants, as the sutures in the skull are unfused, tumours can cause an increase in the size of the head (macrocephaly) with bulging of the anterior fontanelle and dilation of veins in the forehead. Some tumours in infants secrete cerebrospinal fluid, leading to rapid head enlargement. Most tumours in toddlers and young children below 10 years of age involve the lower parts of the brain, such as the cerebellum and brain stem. These Tumours can rapidly block the flow of cerebrospinal fluid, causing early symptoms such as morning headaches, vomiting, and irritability. Tumours arising from the cerebellum can cause unsteadiness in walking and limb tremors, while those involving the brainstem can result in cranial nerve paralysis, leading to double vision, facial deviation, and difficulty swallowing.
Another common type of tumour seen in children affects the pituitary gland and nearby structures. These Tumours can cause hormonal imbalances, such as decreased cortisol, growth hormone, and thyroxine levels. When the hypothalamus is compressed, it can lead to increased appetite, rapid development of obesity, increased urine output (diabetes insipidus), and other symptoms. Advanced imaging techniques such as CT and MRI have made the diagnosis of brain tumours easier. In some cases, additional investigations like angiograms and PET scans may be needed to determine the extent of the lesion before planning surgery. Definitive diagnosis requires a biopsy of the tumour. Less invasive methods like endoscopy and stereotaxic biopsy are available. Tissue samples are tested for various markers that can predict the outcome and help determine the best treatment in many cases.
The management of brain tumours depends on the type of tumour, its location, and the extent of the lesion. Surgery is the most common treatment, followed by radiation and chemotherapy. Complete tumour resection may be challenging if the tumour involves vital structures or important areas of the brain. Newer techniques, such as functional neuroimaging and electrophysiological methods during surgery, as well as gamma knife surgery, can help minimize damage to the normal brain during surgical removal of the tumour. Tumours affecting the pituitary gland and hypothalamus can be operated on through the nose.
Radiotherapy is useful in many Tumours, but it can damage the developing brain and potentially cause long-term difficulties in development and behaviour. Therefore, it is generally avoided as much as possible, especially in children below the age of three. Newer modifications, such as proton beam radiation and thermal therapy using lasers, have been introduced. Chemotherapy, which involves using combinations of drugs to kill or prevent the multiplication of tumour cells, is another treatment modality. These drugs also affect other rapidly dividing cells in the body and can have various side effects. Newer drugs that utilize antibodies and target only the tumour cells have been a valuable addition to treatment options. The selection of these drugs is based on specific markers present in the tumour cells.
In summary, brain Tumours in children form a heterogeneous group with variable outcomes. The use of multimodal therapy, including surgery, targeted chemotherapy, monoclonal antibodies, immunotherapy, and improved radiation methods like proton beam therapy, has improved the prognosis of this condition.
Children with malignant brain tumours and their parents endure significant hardships due to the substantial economic burden on the family, residual deficits caused by the tumour compressing brain tissue, as well as the effects of surgery, chemotherapy, and radiation. Survivors often face behavioural problems, learning difficulties, and hormone deficiencies (in the case of pituitary Tumours), requiring lifelong hormone supplementation. They require support from society. Every year, Brain Tumour Day is celebrated on June 8th to raise awareness about this condition and to provide support to patients and caregivers.
(Dr D Kalpana is a Consultant at the Department of Paediatric Neurology, KIMSHEALTH, Thiruvananthapuram)