A brain tumor is an abnormal development of cells that come from components of the brain, called primary tumors, or can start with cancer in other parts of the body and spread to the brain: secondary or metastatic brain tumors. Some brain tumors are benign and others are cancerous or malignant.
Brain tumors account for up to 20% of all childhood cancers. In children, 70% of primary tumors originate in the posterior fossa, while in adults this proportion corresponds to supratentorial ones.
In adults, there is a similar incidence of primary and metastatic tumors. Malignant primary brain tumors are among the most difficult cancers to treat, with a 5-year survival rate of no more than 35%. 85-90% of primary central nervous system (CNS) tumors are found in the brain.
Causes of tumors in the Central Nervous System
In 2016, the World Health Organization (WHO) described the most complete and updated CNS tumor classification system to date. This classification system classifies CNS tumors not only according to histological type, but also according to molecular markers of cytodifferentiation.
The classification proposes elementary demographic characteristics such as age and genomic and cytodifferentiation aspects, but it also covers therapeutic aspects such as response to treatment and survival.
This new proposal aims to group patients based on the different glioblastoma subtypes and constitutes an important step towards the development of individualized treatments, which have as their objective the defined genetic alterations of each tumor. They are classified in:
- Diffuse astrocytic and oligodendroglial tumors
- ependymal tumors
- Pineal region tumors
- embryonal tumors
- Cranial and paraspinal nerve tumors
- Germ cell tumors
- Sellar region tumors
- metastatic tumors
how to diagnose it
The different types of tests and methods for diagnosing the tumor are mentioned below.
Physical and neurological examination
The initial symptoms of brain tumors are fickle. The brain tumor can appear in any part of the brain, so it can cause symptoms depending on its anatomical location. It is for this reason that they are sometimes so difficult to diagnose.
Symptoms can be classified into two types:
- Focal symptoms, due to the pressure and destruction generated by the tumor in a structure of the brain and that are manifested through epileptic seizures and neurological deficit.
- General symptoms, which are caused by increased pressure inside the head. These are manifested through increased intracranial pressure, headache, nausea and vomiting.
Imaging techniques represent a primary and complementary tool that allows determining the location of the tumor, its appearance, the number of lesions, size and affected areas. They also detect possible complications associated with the tumor, such as the presence of hemorrhage.
The CT (Computerized Axial Tomography): it is a very fast X-ray based test that is used in screening, it is usually the first test that is carried out on a patient with suspected brain tumor.
Nuclear magnetic resonance uses a system that works by applying a powerful magnetic field. The duration is greater than that of the TAC.
Magnetic resonance spectrography is a test that allows the analysis of brain metabolism in vivo and provides non-invasive biochemical information on tissues.
Dynamic resonance allows us to determine if a new vascularization is being generated for the tumor.
Single photon emission computed tomography (SPECT) is very useful in differentiating benign from malignant tumors and predicting the histological grade of tumors to select the area for biopsy. It has also been used to differentiate low-grade and high-grade gliomas.
Positron emission tomography. Positron emission tomography (PET) with fluorodeoxyglucose (FDG) is used to detect malignant tumors with high metabolic rates, since it captures a greater amount of glucose.
This can help the neurosurgeon to locate the areas of the brain with the most aggressive biological behavior, and allows functional areas to be located before surgery or radiation. In addition, PET is useful in determining whether a patient may benefit more from radiation therapy or chemotherapy.
Biopsy is essential and necessary to make the diagnosis. It is the only test that allows microscopic analysis of a sample of the tumor to confirm the definitive diagnosis, which is essential to plan the appropriate treatment.
Keywords: brain tumor
- Lapointe S, Perry A, Butowski NA. Primary brain tumors in adults. Lancet. 2018 Aug 4;392(10145):432-446
- Louis DN, Perry A, Reifenberger G, von Deimling A, Figarella-Branger D, Cavenee WK, et al. The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Act Neuropathol. 2016 Jun;131(6):803-20