There are many types of brain tumors, but they all have one thing in common: There is limited space in our bony skull, and the tumors take up space that is missing from healthy brain tissue. This situation is not without problems and can lead to serious, lasting damage.
Shapes: What brain tumors are there?
Brain tumors, like all other tumors, are uncontrolled cell proliferations of a particular cell type. The brain consists on the one hand of nerve cells (neurons) and on the other hand of the most diverse cells such as glial and oligodendroglial cells, which supply the nerve cells with nutrients and envelop them with connective tissue.
The brain is protected from shocks and padded by the bony skull, several meninges and a fluid, the cerebrospinal fluid. This cerebrospinal fluid is produced and filtered in the brain ventricles, which are several chambers in the brain. The cerebrospinal fluid flows out of these chambers through several openings, washing around both the brain and the spinal cord.
Cerebral ventricle and brain consist of different types of cells, and yet other cells, the plexus cells, produce the cerebrospinal fluid. From all these cell types, tumors can be produced, which are named after their tissue of origin: gliomas, oligodendrogliomas, plexus papillomas. If a tumor is malignant, then the tumor cells under the microscope hardly resemble the cells from which they originated.
Blastomas and brain metastases
The physician expresses this appearance with the name of the tumor: Such tumors are called blastomas, for example glioblastoma. A common brain tumor in children, the medulloblastoma, arises from so-called embryonic tissue, that is, the cells of origin of the tumor had not yet developed into definitive cell types.
The most common brain tumor, the meningioma, is actually not a tumor of the brain, but an overgrowth of the soft meninges. Meningoma is traditionally counted as a brain tumor.
Besides these tumors, there is the group of brain metastases. About 20 percent of all brain tumors are colonies of other tumors, with more than half of all metastases being from bronchial carcinoma and one third from breast cancer. Especially with these two tumor types, it can also lead to a generalized scattering of tumor cells in the meninges, the so-called meningitis carcinomatosa, which has a particularly unfavorable effect on the course of the disease.
Who is affected by brain tumors?
Although brain tumors account for only about two percent of all tumors, they can occur at all ages and, together with leukemia and lymphatic cancers, are the most common tumors in children. On closer inspection, there are two age peaks, on the one hand the infantile tumors and on the other tumors, which occur between the 40th and the 60th year of life.
The tumors differ in their age distribution: While the medulloblastoma occurs in childhood, meningioma and glioblastoma are found in older patients.
So far, no risk factors have been found that favor the appearance of a brain tumor, only the irradiation of the nervous system (even for therapeutic purposes, for example, in a leukemia) seems to be a risk factor especially in childhood. In addition, there are rare hereditary tumors that often form tumors in the nervous system.