‘Metastasize’ means to spread, grow or change form. In pathology (the science of disease), ‘metastasize’ describes the spread of cancer cells from the primary site of the disease to other parts of the body. From primary sites such as the lungs, breasts, kidneys, bladder or skin, tumor cells can spread via the circulatory system (or, in the case of leukemia and lymphoma, can originate within it) to the brain.
Metastatic brain tumors (also referred to as brain metastases, secondary brain tumors or metastasis to the brain) are the most common type of brain tumor in adults. The majority of them are discovered after the primary cancer has already been diagnosed, when a cancer patient first experiences neurological symptoms and undergoes a CT or MRI scan. In rarer cases, a person with neurological symptoms (or requiring imaging for other medical reasons) and no history of cancer may undergo a brain scan that leads to the discovery of brain metastases. Over 80% of metastatic brain tumors arise as multiple lesions in the brain (with fewer than 20% manifesting as a single tumor), and over 80% of all lesions appear in the cerebrum (the uppermost, largest, most recently evolved part of the brain that receives the majority of blood flow).
The signs and symptoms of metastatic brain tumors are the same as any expanding intracranial (within the skull) lesion. They result from the pressure the metastases put on the surrounding tissue, from edema (fluid-based swelling) or from hemorrhage (bleeding). Symptoms vary based on the location of the tumor within the brain and include headaches, seizures, cognitive difficulties (loss of memory or changes in personality or behavior), weakness in an area of the body, decreased coordination or issues with vision, numbness, tingling or other sensation.
As cancer therapies have improved, an increasing number of cancer patients are living longer. Unfortunately, increased patient life expectancy gives cancer cells greater opportunity to spread from their primary sites, causing the incidence of metastatic brain tumors to rise as well. Thus, techniques for treating intracranial tumors, such as Gamma Knife radiosurgery, are vital components of the fight against cancer. Utilized by doctors at the Boston Gamma Knife Center
at Tufts Medical Center to limit the growth of small or delicately situated metastases, Gamma Knife radiosurgery isn’t traditional surgery—no incisions are made. Instead, this state-of-the-art technology focuses 192 beamlets of gamma radiation on the tumor, delivering a high dosage at the site of convergence while saving the vital surrounding tissue from radiation’s harmful effects.