Carolyn Vachani, RN, MSN, AOCN Modified by: Lara Bonner Millar,
MD The Abramson Cancer Center of the University of Pennsylvania
Last Modified: February 10, 2012 Differing between these two
types of brain lesions is a common source of confusion for many
people. Primary brain tumors are tumors that start in the brain,
and are actually quite rare, with an estimated 22,020 new cases
in 2010. Brain metastases, commonly called "brain mets" are far
more common, and are tumors that have traveled to the brain from
another area of the body. It is estimated that between
100,000-170,000 patients develop brain metastases each year.
Let's use an example to better understand this latter concept: a
lung cancer is first formed in the lung tissue, but tumor cells
can break off from the original mass and travel through the
bloodstream or lymph system to other areas of the body,
including the brain. This spreading of the tumor is known as
"metastasis". When a lung cancer metastasizes to the brain, this
"brain tumor" is actually