Metastatic brain cancer

Metastatic brain cancer, which occurs when cancer cells break off from a tumor in the brain and travel to other parts of the body, is extremely rare. It is more common for cancers in other locations in the body to travel, or metastasize, to the brain. Secondary brain tumors, or brain metastases, are much more common than primary brain tumors.

Cancers that commonly metastasize to the brain include lung, breast, colorectal, kidney, melanoma, thyroid and uterine cancers. Lung cancer is the most common form of brain metastases. In fact, lung cancer procedures used to stage the disease often involve a brain scan. Cancers that travel to the brain are still identified by the location in which they originated. For example, metastatic lung cancer found in the brain is still considered lung cancer, not brain cancer.

Metastatic brain cancers will likely be assessed through the TNM (which stands for tumor, node, metastasized) staging system. Sometimes, tumors are found in the brain or spinal cord and diagnosed as metastases that had spread from another location in the body, even before the primary cancer is detected. In some cases, the originating tumor may never be found. This is called cancer of unknown primary (CUP) and occurs in up to 5 percent of all cancers.

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