Brain Metastases

Brain metastases are cancerous tumors that spread from another organ where they originated to the brain, typically by the bloodstream. While not technically a brain cancer since they did not originate in the brain itself, these cancers are the most common malignant tumor in the brain, occuring more often than primary brain tumors.

Many types of cancer can metastasize (spread to distant organs). The most common to spread to the brain are lung, breast, melanoma, renal and colon cancers. Occasionally, tumors can spread to the brain by direct invasion rather than by spread through the bloodstream. For example, malignant tumors of the skull (such as chondrosarcoma or osteosarcoma), nasopharyngeal and oropharyngeal carcinomas can grow up into the brain from adjacent tissues.

The symptoms of brain metastasese can vary greatly depending on the size and location of the metastatic tumor in the brain. However, in general, they are the same types of symptoms that can occur with any other type of brain cancer. Common symptoms include new onset of seizures in an adult patient, headaches, or weakness of the opposite side of the body.

The diagnosis of brain metastases can be reached by various means. In a patient who presents with symptoms referable to the brain, a CT or MRI scan may reveal the brain tumor. However, in some patients without symptoms a work up for metastases may be undertaken after their primary cancer is discovered. A screening CT or MRI of the brain may reveal these metastases to the brain, even before symptoms have begun. Final confirmation of the diagnosis can only be made definitively once some tumor tissue can be sampled and examined by a pathologist.

Treatment of metastatic brain tumors varies depending on several factors including size, number of tumors in the brain, location, symptoms and the general condition of the patient with regards to the general effect of the cancer in the patient's body. In terminal cases no treatment, or only palliative treatment, may be administered. In patients who have only one or few metastases, surgical or radiotherapy treatment of the brain metastasis may be offered. More general brain radiation therapy may be undertaken in patients with multiple brain mets. Chemotherapy is often offered to these patients as well, along with treatments focused on the primary tumor of origin.

Prognosis for patients with metastatic brain tumors is generally poor. Spread of cancer to distant organs is generally a sign of very advanced disease and involvement of the brain is one of the most feared outcomes of various cancers. However, in some patients with a well controlled primary tumor and only limited brain disease, treatment may prolong survival.