Cancer remains one of the diseases with the highest morbidity and mortality in the world, meaning the highest rate of deaths from disease. It is estimated that in 2020, more than 19 million cases were diagnosed worldwide and 10 million people died from this disease [1]. Of the diagnosed cases, approximately 308,000 people suffered from some type of primary brain tumor, such as glioma.
Brain cancers are among the 10 leading causes of death among men and women worldwide. Specifically, glioma accounts for 33% of the tumors that cause this type of cancer [3]. If you want to know more about it here we explain the most relevant data about this disease: what it consists of, what are its causes, what genetics has to do, what type of brain gliomas exist and what options we have to detect them in time.
What is a glioma?
Glioma is a type of tumor that occurs in the brain or spinal cord. It is called a glioma because it arises from glial cells (or neuroglial cells), the slimy support that surrounds nerve cells in order for them to function properly. Of the four types of glial cells that exist in our body (astrocytes, oligodendrocytes, microglia and ependymal cells), three can produce tumors.
Types of gliomas
Depending on the type of glial cell causing the tumor, there are different types of gliomas [4]:
- Astrocytomas: related to astrocytes. It’s the most common form of brain tumor and usually appears in the cerebrum, although sometimes it also appears in the cerebellum. It is a type of tumor that can occur at any age [5]. This includes astrocytomas, anaplastic astrocytomas and glioblastomas.
- Ependymomas: Caused by ependymal cells. This type of tumor is rarer and accounts for less than 5% of all primary brain tumors. However, its incidence reaches 10% in the case of childhood brain tumors. It usually occurs in the brain or spinal cord [5]. It includes anaplastic ependymomas, myxopapillary ependymomas and subependymal gliomas.
- Oligodendrogliomas: Generated by oligodendrocytes. They usually appear in the frontal and temporal lobes and account for 5% of primary brain tumors. Their incidence is higher among young people and adults and is more common in men [5]. They are oligodendrogliomas, anaplastic oligodendrogliomas and anaplastic oligoastrocytomas.
Glioma symptoms
Depending on the type of glioma involved, its location, size and speed of growth, symptoms may vary. As brain tumors, symptoms usually appear suddenly and among the first and most common symptoms are headache and nausea [6], although the following glioma symptoms have also been documented:
- Amnesia or memory loss.
- Vision problems, such as double vision, blurred vision, or loss of peripheral vision.
- Speech difficulties.
- Balance problems.
- Confusion or decreased brain capacity.
- Irritability or personality changes.
- Seizures.
- Urinary incontinence.
Glioma causes
As in almost any type of tumor, glioma causes are not yet known exactly, but there are a number of factors that are considered risk factors when it comes to being more prone to developing this type of brain cancer. Some studies highlight the following among the main risk factors for glioma [4,7]:
- Age: The risk is increased as one gets older. Gliomas tend to affect a greater proportion of people between 45 and 65 years of age.
- Exposure to ionizing radiation: It has been shown that previous treatment of the brain with ionizing radiation, including X-rays, may increase the likelihood of developing a brain tumor. This type of radiation would include radiotherapy and that caused by atomic bombs, among others.
- Exposure to infections, viruses and allergens: There is still much research to be done in this field, but so far an increased risk of brain tumor has been detected in people who have been infected by the Epstein-Barr virus, known as the virus that causes mononucleosis or kissing disease. In addition, traces of cytomegalovirus have also been found in brain tissue in people with glioma. On the other hand, it seems to have been demonstrated that people with a history of allergies, skin disorders, allergic rhinitis or asthma have a lower risk of developing this type of cancer.
- Family history: Although it is not a determining factor, having a family history of glioma may increase the risk of developing it.
Genetics and glioma
About 5% of people with glioma have close relatives with the same diagnosis [5]. In addition, in recent years, great strides are being made in genetic research into diseases such as brain cancer, and more and more data are becoming known that could indicate a stronger relationship between genes and the risk of glioma. For example, an association has been seen between glioma and mutations in the TERT gene, which codes for an enzyme called telomerase reverse transcriptase, which maintains the ends of telomeres. Telomere shortening is a mechanism for controlling proliferation and preserving the integrity of the genome, which explains the relationship between the alteration of this gene and, therefore,thus the pathway that maintains telomere ends, with different types of cancer, including glioma.
At 24Genetics we search your DNA for genes related to a higher propensity to suffer from glioma and many other types of cancers and diseases. Thanks to our health test, we can provide you with essential information for an early diagnosis of a multitude of ailments at the onset of the first symptoms. In addition, our team of expert geneticists are available to answer any questions you may have.
Bibliography
[1]Cancer killed ten million people in 2020, most in low- and middle-income countries – United Nations. UN News. Global Look Human Stories [published Feb. 2021; accessed Dec. 2022] Available at: https://news.un.org/es/story/2021/02/1487492
[2] Brain tumor: statistics. – Cancer.net. Approved by Cancer.Net Editorial Board, 02/2022 [published Feb. 2022; accessed Dec. 2022] Available from: https://www.cancer.net/es/tipos-de-c%C3%A1ncer/tumor-cerebral/estad%C3%ADsticas
[3] Conditions We Treat: Gliomas, Astrocytomas, and Glioblastomas – Johns Hopkins Medicine [accessed Dec. 2022] Available at: https://www.hopkinsmedicine.org/international/espanol/conditions-treatments/neurosurgery/gliomas.html#:~:text=A%20glioma%20is%20a%20type,%20found%20in%20the%20brain.
[4] Glioma – Mayo Clinic [accessed Dec. 2022] Available at: https://www.mayoclinic.org/es-es/diseases-conditions/glioma/symptoms-causes/syc-20350251
[5] Glioma: types, causes, symptoms and treatment options – Pacific Gamma Knife [published May. 2020; accessed Dec. 2022] Available at: https://blog.gammaknifedelpacifico.com/glioma-causas-sintomas-y-opciones-de-tratamiento
[6] The early symptoms of glioma: how the most common brain tumor starts at an early age – Pablo García Santos [published Jul. 2022; accessed Dec. 2022] Available at: https://www.elespanol.com/ciencia/salud/20220721/sintomas-tempranos-glioma-empieza-cerebral-frecuente-temprana/689181144_0.html
[7] Brain tumor: risk factors – Cancer.net. Approved by Cancer.Net Editorial Board, 09/2021 [published Sep. 2021; accessed Dec. 2022] Available at: https://www.cancer.net/es/tipos-de-c%C3%A1ncer/tumor-cerebral/factores-de-riesgo
