Brain tumors can originate from many different types of brain cells. This is significant because a brain tumor is named for the cell from which it originates.
Brain tumors can also be benign, meaning they are less aggressive.
Even so, benign brain tumors can be problematic depending upon the area of the brain they effect. Certain brain tumors may not only spread in the brain but also into the spinal cord. It is rare for primary brain tumors to spread outside the central nervous system. The most common cancers that spread to the brain are lung, breast, kidney and skin. Instead, it would be diagnosed, for example, as lung cancer with metastases to the brain.