Metastatic tumors are the most common neoplasm in the brain, occurring in 24-45% of all cancer patients and accounting for 20% of cancer deaths annually. These rates are on the increase due to a boost in survival of patients with cancer because of modern therapies along with increased availability of advanced imaging techniques for early detection. Newer therapies such as immunotherapy prolong overall survival in some cancers such as Melanoma but like many other chemotherapy drugs penetrate the CNS poorly, leaving the brain a safe haven for tumor growth.
Approximately 60% of patients with brain metastases will present with subacute symptoms. Symptoms are usually related to the location of the tumor and may include headaches, seizures, cognitive or motor dysfunction Radiological investigation provides information on tumor burden in the brain and associated structures, in addition to the rest of the body, and are integral part in formulating the treatment plan. CT brain is the initial investigation in most cases and a useful screening tool. Further imaging studies should include the following: CT or PET to assess systemic disease and MRI to better define the anatomy of the tumour and assess for other cerebral lesions. Up to 75% of patients with brain metastasis will have multiple lesions
Initial medical management of metastatic disease focuses on the treatment of symptoms such as headache from cerebral oedema with corticosteroids (dexamethsone) or seizures with anti-convulsants.
Most Brain metastasis are not chemosensitive and treatment mainstays are surgery and radiotherapy. Radiation therapy includes whole brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS). SRS is a becoming a preferred treatment modality due to more favorable side effect profile and better local control rates up to 95%. It is also frequently used to treat the resection cavity of brain metastasis post-surgery.
Surgical resection is considered standard care for solitary metastases larger than 3 cm and in non-eloquent areas of the brain in patients with good performance status, controlled systemic disease.
Surgery is also an option in cases where there is a dominant symptomatic lesion with multiple other asymptomatic lesions. Surgery is contraindicated in the case of radiosensitive tumor (e.g., small-cell lung tumor), patient life expectancy < 3 months, and usually in patients with multiple lesions.
The development brain metastasis represents a difficult and significant time for any patient. As always the treatment must be tailored to the individual patients needs and requires the collaboration of neurosurgeons, oncologists, and General Practitioners.