Primary brain tumors are cancers that arise in the brain rather than spreading to the brain from other parts of the body.

Primary brain tumors make up about 1 percent of all cancers in the United States (13,000 cases a year) and cause roughly 2.5 percent of all cancer deaths.

These are the most common solid tumors in children. In adults, there is a steady rise in incidence with age, the peak occurring between the ages of 50 and 55.

The brain also is a frequent site of metastasis for other tumors,...