Oligodendroglioma

Oligodendroglioma is a type of glioma, a tumor that originates from oligodendrocytes, the cells that myelinate neurons in the central nervous system. Oligodendrogliomas are slow-growing and can occur in various parts of the brain, primarily in the frontal and temporal lobes. Pathological changes associated with oligodendrogliomas include the presence of characteristic mutations in the IDH1 and IDH2 genes, as well as the loss of chromosomes 1p and 19q. These tumors can be either low-grade (WHO I–II) or high-grade (WHO III–IV), and require an individualized approach to diagnosis and treatment. The clinical picture of oligodendrogliomas can vary, including neurological deficits, seizures, and changes in mental status depending on the tumor location.

History of the disease and interesting historical facts

The history of oligodendroglioma research dates back to the early 20th century, when their macroscopic and microscopic structure was first described. The first scientific papers were devoted to the study of histopathological characteristics of brain tumors. In 1926, the French neuropathologist T. Roland began to systematically classify gliomas, including oligodendrogliomas. In 1979, significant progress was made in understanding the molecular mechanisms of oligodendrogliomas, when common genetic changes such as chromosomal deletions of 1p and 19q were identified. These discoveries led to a revision of tumor classifications and a deeper understanding of the pathogenesis of oligodendrogliomas, which in turn opened up new horizons for the development of targeted therapy.

Epidemiology

According to statistics, oligodendrogliomas account for about 5-10% of all gliomas and 1-2% of all brain tumors. These tumors are most common in adults aged 30 to 50 years and are slightly more common in men than in women. According to the journal Neuro-Oncology, the incidence of oligodendrogliomas in the United States is 0.4-0.5 cases per 100,000 people per year. In European countries, the rates are similar. It is also noted that oligodendrogliomas are more often diagnosed in people with a genetic predisposition, in particular, in those who have hereditary syndromes, including Li-Fraumeni syndrome and neurofibromatosis type 2.

Genetic predisposition to this disease

Genetic predisposition to oligodendrogliomas is largely associated with the presence of mutations in genes that affect the cell cycle and apoptosis. The main genes involved include IDH1 and IDH2, which encode isocitrate dehydrogenase, a key enzyme involved in the metabolism of α-ketoglutarate. Mutations in these genes are found in 60-80% patients with oligodendrogliomas. In addition, the chromosomal loss of 1p and 19q, which is characteristic of oligodendrogliomas, is considered a sign of a better prognosis and is more often observed in low-grade forms of the tumor. Other genes, such as TP53 and ATRX, may also be involved in the pathogenesis, which creates a complex picture of the molecular basis of this disease.

Risk factors for the development of this disease

There are both physical and chemical risk factors associated with the development of oligodendroglioma. The main ones include:

• Exposure to ionizing radiation: People who have been treated with radiation for other conditions have an increased risk of developing oligodendrogliomas.
• Genetic predispositions: Having syndromes such as Li-Fraumeni or neurofibromatosis type 2 increases the likelihood of developing oligodendrogliomas.
• Exposure to chemical carcinogens: Research evidence also suggests a link between exposure to chemicals such as solvents and pesticides and an increased risk of brain tumors.

It is worth noting that lifestyle factors such as smoking and alcohol consumption have not been established as significant in the development of oligodendrogliomas, unlike other types of tumors.

Diagnosis of this disease

The main symptoms of oligodendrogliomas can vary based on their location, but the most common ones include:

• Headaches of varying intensity;
• Convulsions, often focal;
• Neurological deficits (eg, weakness or sensory disturbances);
• Changes in cognitive functions;
• Change in behavior or personality.

The following methods are used to diagnose oligodendroglioma:

• Laboratory tests: A complete blood count can help rule out other diseases, but there are no specific markers for oligodendrogliomas.
• Radiological examinations: Magnetic resonance imaging (MRI) is the method of choice to visualize the tumor. Computed tomography (CT) can be used to evaluate the presence of edema and hemorrhage.
• Histopathological examination: performed after surgical removal of the tumor and establishment of a final diagnosis.
• Differential diagnosis: includes MS, metastatic tumors and other primary brain tumors.

Treatment

Treatment of oligodendroglioma can be complex and depends on the stage of the disease, its location and the general condition of the patient. The main approaches to treatment include:

• Surgical treatment: radical resection is the preferred method for tumors accessible for surgery. In local or invasive forms, stereotactic radiosurgery may be indicated.
• Pharmacological treatment: the use of chemotherapy, usually in highly malignant forms. Temozolomide-based drugs are widely used.
• Radiation therapy: used both postoperatively to control any remaining tumor and as primary therapy if tumor removal is not possible.
• Other treatments: In rare cases, innovative methods such as immunotherapy and gene therapy are used, but they are in the clinical trials stage.

List of medications used to treat this disease

The most commonly used drugs to treat oligodendrogliomas include:

• Temozolomide;
• Sotilimuz (Sunitinib);
• Lomustine;
• Carmustine;
• Tekerab (Tafasitamab);
• Everolimus.

Disease monitoring

Monitoring of patients with oligodendrogliomas includes regular follow-up examinations with MRI to assess possible disease progression or recurrence. Prognosis depends on a number of factors, including the grade of malignancy and the presence of specific genetic mutations. In general, 5-year survival for low-grade oligodendrogliomas is up to 80%, while for high-grade forms it is lower and is about 20-30%. Complications after treatment may include neurological deficits and adverse reactions to chemotherapy, which requires careful rehabilitation.

Age-related features of the disease

Oligodendrogliomas may present differently depending on the age group. Children have a more favorable course, while adults, especially after 40 years, experience a significantly increased variety of forms and aggressiveness of tumors. Older patients also experience a deterioration in their general condition, which can complicate treatment. Understanding these age-related features contributes to a more targeted approach to diagnosis and treatment of the disease.

Questions and Answers

• What is oligodendroglioma? Oligodendroglioma is a brain tumor that forms from oligodendrocytes and is characterized by slow progression and the presence of specific genetic mutations.
• What are the diagnostic methods for oligodendroglioma? MRI, CT, histopathological examination and analysis of clinical symptoms are used to diagnose oligodendroglioma.
• How is oligodendroglioma treated? Treatment includes surgical resection of the tumor, chemotherapy and radiation therapy, the choice of which depends on the degree of malignancy and other factors.
• What risk factors may influence the development of oligodendroglioma? Risk factors include ionizing radiation, genetic predisposition, and exposure to chemical carcinogens.
• What is the prognosis for oligodendroglioma? The prognosis depends on the degree of malignancy and the presence of specific chromosomal deletions, but in general, survival in low-grade forms is high.