Metastatic Tumors to Brain

Three mechanisms have been described for the development of metastases. For parenchymal lesions, the most common is hematogenous spread. Metastatic lesions are usually found at the junction between gray and white matter. Metastasis can also occur via local extension from the primary tumor, such as in head and neck cancer, and via bodily fluids, such as the CSF.

Clinical Manifestations. Patients with brain metastases can present with a variety of clinical features. Thus any patient with a history of cancer who develops new neurologic symptoms warrants careful examination. About half of the patients will present with headaches with increasing frequency when multiple lesions or posterior fossa lesions are present. Other common symptoms include focal weakness and mental status changes. Up to one fifth of patients will present with seizures. Strokes can also occur in the setting of metastasis. This may be due to general hypercoagulability, disturbance of arterial flow, tumor embolization, or hemorrhage into a lesion. Melanoma, renal cell carcinoma, thyroid cancer, and choriocarcinoma have a propensity to bleed.

Diagnostic Studies. Contrast magnetic resonance imaging (MRI) is preferred for the diagnosis of brain metastasis because it is more sensitive in detecting lesions and differentiating metastatic lesions from other central nervous system abnormalities. Parenchymal brain metastasis tends to be circumscribed with large amounts of surrounding vasogenic edema relative to the size of the lesion. The presence of multiple lesions and location at the gray and white matter junction further supports a diagnosis of metastasis. Because metastatic lesions can also spread via CSF fluid, examination of CSF fluid may be necessary in some patients to evaluate for the presence of leptomeningeal involvement. Finally, if the diagnosis of metastasis is still in doubt, a biopsy should be performed for confirmation.

Treatment. The treatment plan for patients with brain metastases depends on their prognosis, which is based on their performance status, extent of extracranial disease, age, and primary diagnosis. In those patients with a favorable prognosis, treatment is aimed toward eradication or control of brain metastasis. This involves surgical resection combined with radiotherapy to eliminate residual cancer cells. Randomized trials have shown that the addition of whole brain radiation (WBRT) to surgery reduces recurrence rate but does not improve overall survival. In some cases, surgery is not a reasonable option, thus stereotactic radiosurgery (SRS) is considered. Combining WBRT with SRS seems to improve progression free survival but does not impact overall survival. In patients considered to have a poor prognosis, treatment is focused on symptom management and maintenance of neurologic function. In these cases, WBRT is preferred in order to improve neurologic deficits and prevent further deterioration. In both patient groups, corticosteroids are often used to control symptoms from mass effect and edema.

Only gold members can continue reading. Log In or Register to continue