Tumor Types > Metastatic Tumors
Metastatic tumors do not start in the brain. They travel to the brain from tumors (usually cancerous) which have started in some other part of the body - such as the lung, kidney or bowel. These individual tumor cells usually get from their primary site to the brain via the blood stream. Upon reaching the capillary blood vessels of the brain, the tumor cells take root and there continue to grow as another tumor. Sometimes multiple metastatic tumors are formed and can be found in different areas of the brain.
The most common sites of the primary tumor which can spread to the brain are: lung, bowel, breast and kidney. It is also not uncommon for melanomas (a form of skin cancer) to travel to the brain. Metastatic tumors arising from locations within the paranasal sinuses tend to grow directly into the skull. Other tumors, transmitted along the venous network to the brain, usually grow between the skull and the brain.
Metastatic tumors are as malignant as the cancerous primary tumor from which it came. Most grow quickly and as the tumor enlarges, it recruits its own blood vessels to noourish itself. In addition, some inflammatory response occurs, causing the brain around the tumor to swell (edema). Usuallyn - but not always -the edema of a metastatic tumor is more pronounced than that of a primary tumor which has started in the brain. Edema adds to the mass effect and can cause dysfunction of the surrounding normal brain.
Symptoms of a Metastatic Brain Tumor
The symptoms of any brain tumor will depend on the size of the tumor and the area of the brain involved. Large tumors can raise intracranial pressure while smaller tumors might make their presence known by producing seizures. These seizures can be focal (muscular twitching) or paresthesias (pins and needles sensation) and involve the face, arm or leg.
The mass of the tumor plus the volume of swollen brain around the metastatic tumor can irritate surrounding brain tissue and cause seizures. Additionally, if the metastatic tumor is located in an important part of the brain, the surrounding edema can impair normal functioning of the brain. Neurological deficits ensue, such as: weakness of face, arm or leg, trouble with speech or problems with walking, balance, memory or thinking. Finally, with a large metastatic tumor and associated edema, pressure inside the skull increases and can cause sleepiness, coma and eventually death. With early detection and proper diagnosis, treatment for those with metastatic tumors will prevent much of the above from happening.