Brain cancer: causes, risk factors and statistics

What can cause brain cancer?

• Genetic predisposition
• Influence of negative factors
• Congenital Syndromes

What is brain cancer?

Brain cancer is a common name for some intracranial grows. They are divided into primary tumors(about 2% of all cancers) and secondary ones. Primary tumors occur from the tissues of the brain and its membranes. Over 60% of primary tumors are benign. Secondary brain tumors are the result of cancer metastasis localized in another part of the body.

In adults, brain tumors occur most often in the central brain region called the cerebrum (latin cerebrum). About a quarter of brain and central nervous system tumors (24%) originate in the membranes (brain membranes) surrounding and protecting the brain. And about 1 in 10 (10%) tumors are formed in such parts of the brain as the pituitary or pineal body.

Children show other figures. 6 out of 10 tumors (60%) of the brain in children develop from the cerebellum or brainstem. And only 4 out of 10 (40%) are directly in the brain.

Brain cancer includes 4 types of tumors:

• Neuroepithelial tumors (developed from brain tissue) include gliomas and astrocytomas.
• The tumor of the cranial nerves is cancer of the myelin sheath of the nerve, for example, neurinoma.
• Tumors of the brain membranes are the grows in the cells of the arachnoid membrane of the brain (meningiomas).
• Metastatic tumors occur when cancer in another organ or tissue of the body metastasize. For example, a spread of breast cancer.

The causes of brain cancer development are not exactly revealed. But some risk factors are closely associated with an increased probability of the disease developing.

The leading causes of brain cancer:

• Genetic causes
• Ionizing radiation
• Chemical substances

The genetic causes of brain cancer

The genetic factor causes only 5-10% of brain tumors. If one of your close relatives (parents, brother, sister) has brain cancer, then you automatically are in a risk group.

The probability of developing brain cancer is affected by a specific type of genes (oncogenes). A particular role is played by heredity and the so-called growth factors, which stimulate cell growth. So, the development of glioblastoma is influenced by the epidermal growth factor. An astrocytoma (one of the most common tumors in children) in 15% of cases occurred due to damage to the gene NF1.

The risk factors of this group include some syndromes (congenital conditions) caused by a disorder in the structure of specific genes:

• Neurofibromatosis of the 1st and 2nd types (diseases of the NF1 and NF2 gene);
• Turco Syndrome (changes in the APC gene);
• Gorlin syndrome or basal cell nevus syndrome (disorder of the PTCH gene);
• Tuberous sclerosis, or Burnevil's disease (damage of the TSC1 and TSC2 genes);
• Li-Fraumeni syndrome (destruction of the TP53 gene).

Most of the changes at the gene level leading to brain tumors are not hereditary. Changes can occur due to the impact of adverse environmental factors or other harmful effects on DNA (viruses, hormonal failures, toxins) that can provoke the development of cancer.

Irradiation as a cause of brain tumor development

Ionizing radiation as a risk factor is considered for people working in the field of nuclear energy, radiology or for those patients who underwent radiation therapy. Radiation is associated with a high risk of meningiomas and malignant gliomas development.

Meningioma is the mostly benign tumor that develops from the cells of the arachnoid (endocrine) tissue surrounding the brain.

The effect of chemicals on brain cancer development

Chemicals increase the risk of developing brain cancer among people working in hazardous industries, especially those related to the production of plastics.

Other risk factors

• Sex. Brain cancer in men is more common than in women (except meningiomas).

• Age. The most of tumors develop in adults and people in old age. But children may also have cancer of the brain and spinal cord. Brain tumors take the 2nd place among the most common types of cancer (after leukemia).

• Ethnicity. Primary brain tumors are more common in white people, so the risk of glioma is twice higher.

• Health status. In people with the weakened immune system (HIV, AIDS, after organ transplants or transplantation), the chance of developing brain cancer and other oncological diseases increases.

Brain cancer statistics in adults and children

There are over 120 primary types of brain tumors, but not all of them 0are malignant.

The chances that an average person will develop a malignant tumor of the spinal cord or brain is under 1% (about 1 out of 140 in men and 1 out of 180 in women).

According to the research, 6-28% of patients have the risk of metastasis development to the brain.

Approximately 80% of malignant grows to metastasis to the brain. This group includes, for example, melanoma (50% of cases give metastases to the brain), lung, breast, kidney and colorectal cancer.

The average survival rates for patients with brain cancer of only 35%

• Men: 32%
• Women: 35%

Glioblastoma is the most common form of primary malignant brain tumors. 5.1% is 5-year survival rate of patients with glioblastoma.

The most common types of brain cancer in adults:

• Meningiomas - 36.4% of all primary tumors
• Gliomas (glioblastoma, ependymoma, astrocytoma, and oligodendroglioma) - 80% of malignant tumors

The average survival rate for all primary children (0-19 years old) malignant brain tumors - 73.6%

The most common types of brain tumors in children (0-14 years old):

• astrocytoma
• malignant gliomas
• medulloblastoma
• neuronal and mixed neuronal-glial tumors
• ependymoma

According to the incidence, primary tumors are divided into:

• 35% of meningiomas
• 16% of glioblastoma
• 14% of pituitary tumors
• 7% astrocytoma
• 9% neurinoma
• 2% of lymphoma
• 33% others (oligodendroglioma, ependymoma, embryonic, etc.)

Statistics on the prevalence and aggressiveness of brain tumors