Brain Cancer (cont.)
IN THIS ARTICLE
Brain Cancer: Primary and Metastatic Tumors
Primary brain tumors
The brain is made up of many different types of cells and tumors that arise from a brain cell type are termed primary brain tumors.
Brain tumors vary in their growth rate and ability to cause symptoms. The cells in fast growing, aggressive tumors usually appear abnormal microscopically. The National Cancer Institute (NCI) uses a grading system to classify tumors. The NCI lists the following grades:
Per the Central Brain Tumor Registry of the United States in 2012, approximately 70,000 brain tumors will have been diagnosed in the U.S. in 2013. About 25,000 will have been malignant, and 45,000 benign (with 22,000 cases being diagnosed as meningioma, the most common form of brain tumor, and usually a benign type). Glioma is the most common type of malignant brain tumor, with at least half being grade IV or glioblastomas, the most aggressive type of malignant brain tumor or brain cancer. This registry is being updated, so only 2012 data is available at this time.
Metastatic Brain Tumors
Metastatic brain tumors are made of cancerous cells that spread through the bloodstream from a tumor located elsewhere in the body. The most common cancers that spread to the brain are those arising from cancers that originate in the lung, breast, and kidney as well as malignant melanoma, a skin cancer. The cells spread to the brain from another tumor in a process called metastasis. The process metastasis occurs when cancer cells leave the primary cancer tissue and enter either the lymphatic system to reach the lymph nodes and possible later the bloodstream or through the bloodstream directly. These cancer cells eventually reach the brain tissue through the bloodstream where they develop into metastatic tumors.
Metastatic brain tumors are the most common type of tumor found in the brain and are much more common than primary brain tumors. Metastatic tumors are usually named after the type of tissue from which the original cancer cells arose (for example, metastatic lung or metastatic breast cancer). Brain blood flow usually determines where the metastatic cancer cells will lodge in the brain; about 85% locate in the cerebrum (the largest portion of the brain, located in the upper part of the skull cavity). Unfortunately, the majority of metastatic brain tumors spread diffusely within the brain and are found at least half the time at more than one site in the brain tissue, appearing as multiple masses on the diagnostic scan.
Fifteen percent of all cancers (except for non-melanoma skin cancer, and carcinoma in situ of the cervix) will be complicated by brain metastases.
Medically Reviewed by a Doctor on 4/10/2015
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