A metastasis of cancer cells in the brain tissue is called brain metastasis. A distinction is made between cancer cells that originate in the brain itself (brain tumor) and cells that originate from malignant tumors outside the brain (brain metastases). Tumors that frequently form brain metastases are lung cancer, breast cancer, malignant melanoma and renal cell carcinoma.
More than half of all tumors located in the skull are brain metastases. Brain metastases can be detected in about 10 to 30 percent of adults with malignant tumors. In addition, a distinction is made between solitary brain metastases, where there is only a single brain metastasis and no further metastases of cancer cells (metastases) elsewhere in the body.
A distinction is made between singular brain metastases (single brain metastases, further metastases at other locations in the body) and multiple brain metastases (several tumors in the head). Brain metastases are usually located in the cerebrum, in rare cases they can also occur in the cerebellum and brain stem. In the area of the brain, brain metastases are the most frequently occurring malignant tumors.
They manifest themselves through a variety of symptoms such as headaches, seizures, neurological deficits (e.g. impaired vision) or changes in character. About one in ten patients is diagnosed with cancer because brain metastases have formed which cause symptoms and complaints (e.g. an epileptic seizure). The treatment of brain metastases depends on many factors. In most cases, the prognosis for brain metastases is rather unfavorable, since the presence of brain metastases always indicates an advanced stage of a tumor disease.
Origin
Brain metastases are metastases of cancers of other organs. This means that the cancer originally started as a so-called primary tumor in a body tissue outside the central nervous system. If individual cells of this primary tumor detach, they can migrate through the body (e.g. via the bloodstream) and settle (metastasize) at another location and multiply there.
If this happens in the brain, it is called a brain metastasis. The exact mechanisms behind the development of a metastasis are not yet fully understood. Also, the fact why, for example, breast or lung tumors frequently form metastases and why other tumors do not show this tendency has not yet been conclusively clarified.
Thus, brain metastases do not contain nerve cells, but are composed of tissue similar to that of the primary tumor. However, since the cells are degenerated cancer cells, it is sometimes not possible to determine the location of the primary tumor in the body with the aid of a microscope. Brain metastases are therefore secondary brain tumors. A distinction is made between “real” brain tumors that originate directly from brain tissue.
