A tumour is an abnormal growth of tissue resulting from the progressive, uncontrolled multiplication of cells.
The onset of this disease is usually due to a genetic mutation of the cell DNA that transforms the cell and the surrounding cell clones. This leads to abnormal growth, ignoring the signals of growth regulation in the surrounding region. Once these cells become invasive, they can infiltrate and penetrate the lymphatic and blood vessels, reaching other parts of the body and forming metastases.
What is the prevalence of brain tumours?
- Brain metastasis is the most prevalent type of neoplastic process in the CNS.
- 15% of patients with systemic neoplasms develop brain metastases.
- The tumours that most frequently spread to the CNS by haematogenous dissemination are lung tumours.
Primary tumours
- Brain tumours are the second most prevalent type of tumour during childhood.
- Malignant brain tumours represent 1% of all cancers.
- Up to one in four tumours in paediatric patients originates in the CNS.
- 80% of malignant brain tumours are formed of anaplastic astrocytomas and glioblastomas.
- The most common benign tumours of the CNS are meningiomas (20–25% of all brain tumours).
- During childhood, the most common tumours arise in the posterior fossa (medulloblastoma, ependymoma, cerebellar astrocytoma, etc.).
- In adults, the most common tumours are supratentorial. The most common supratentorial tumours are glial tumours (astrocytomas, oligodendrogliomas, and glioblastomas) followed by meningiomas.
What’s the prognosis?
The prognosis of brain tumours depends on their degree of malignancy (generally determined by the morphological characteristics of the tumour), other intrinsic factors (the patient’s age, overall health, etc.), the location of the tumour, and the result of the treatment.
- Malignant brain tumours are the second most common cause of death in children and the fifth most common cause of death in adults.
- The average survival rate in children is 50–75% five years after diagnosis.
- The survival rate of patients with multiple brain metastases is very low, and may be as little as 3–6 months in patients undergoing treatment.
What are the symptoms?
Benign tumours
- Many benign tumours such as meningiomas cause very few symptoms until they reach a large size. They are usually discovered accidentally in patients undergoing clinical examination for other reasons.
Malignant tumours
- In general, tumours can cause general (as opposed to local) symptoms such as headaches, vomiting, confusional state, personality changes, lack of balance, etc. and local symptoms depending on the location of the tumour.
- In general, hemispheric tumours cause epileptic seizures, behavioural changes, and focal symptoms similar to those caused by a stroke (motor deficits, sensory problems, language issues, etc.). Depending on their location, hemispheric tumours can cause different topographic syndromes (see: https://irenea.es/tumores-cerebrales/#more-1718)
Metastases
- Metastases in the CNS usually arise as single masses or multiple masses and cause a variety of symptoms depending on the topography. They cause focal symptoms that may be hemispheric, cerebellar, or symptoms of the trunk. Although 20% of metastases are usually asymptomatic, they often have an acute onset, similar to strokes, combining signs of intracranial hypertension (headaches, blurred vision, vomiting) with the aforementioned topographic syndromes.
What are paraneoplastic syndromes?
- Illnesses of this type can lead to clinical signs that are not directly related to cancer of the nervous system and can occur even before the cancer is detected using the latest diagnostic tests.
- With paraneoplastic syndromes, the nervous system becomes damaged by relatively unknown immunological mechanisms.
- In general, these syndromes have acute/subacute symptoms that vary with each case of the syndrome – sometimes it affects one area, and sometimes it affects another. Symptoms include epilepsy, behavioural changes, and cognitive deterioration (in the case of limbic encephalitis) and ataxia, dysarthria, and dysphagia (in the case of cerebellar degeneration).
What are the effects of radiotherapy?
- Although radiotherapy is an important part of the treatment of brain neoplasms, it can cause acute adverse reactions (headaches, vomiting, blurred vision, clinical deterioration), subacute adverse reactions (drowsiness, clinical deterioration), or chronic adverse reactions.
- The chronic effects of radiotherapy tend to be more serious and may even appear several years after receiving treatment.
- In the long term, radiotherapy can cause necrosis in the region targeted by the treatment or more diffuse injury to the white matter.
- Clinically, the long-term effects of radiotherapy can include motor deterioration (weakness, lack of balance, tremor, spasticity), cognitive deterioration (attention problems, psychomotor retardation, learning difficulties), or behavioural deterioration (irritability, apathy).