Not all brain tumors are cancerous. Primary brain tumors, which are tumors that originate in the brain, can be either non-cancerous or cancerous, according to Johns Hopkins Medicine. Secondary brain tumors start as cancer somewhere else in the body before spreading to the brain, so they are always cancerous.
Benign, non-cancerous brain tumors grow slowly and rarely spread, though they can still be dangerous because they are capable of damaging vital parts of the brain, states Johns Hopkins Medicine. Malignant, cancerous brain tumors can grow swiftly and invade surrounding brain structures.
Secondary brain tumors are also known as metastatic brain tumors. They are approximately four times more common than primary brain tumors, says Johns Hopkins Medicine.