What causes brain tumors? All cells in our body have two tremendous qualities; #1) differentiation and #2) self-control. Brain tumors are caused by cells that lose these qualities. "Differentiation" means cells grow up to have specific jobs. To explain this, think of when a single cell is fertilized and one cell becomes two, two cells become four, four become eight, etc. Somehow, over a nine-month period in the mother's womb, those cells get messages to become different from each other. As those cells grow they "differentiate" into different parts of the body. Some cells grow up to be part of the toe, others become part of the brain, or lungs, or skin. These cells have all taken on very specific jobs. Cells also "regulate" themselves. This means they know when the body needs new cells, and they can reproduce themselves and know when to stop. For example, when you are young you keep growing taller, and you need new pants of longer lengths every few months. But once you become 18, 19 or 20 years old, the bones grow to their longest, and the body says "enough is enough" and you stop making bone cells. This is what we call "self-regulation." Tumor cells are cells that have lost the ability to differentiate and have lost their ability to regulate themselves. Tumor cells don't secrete evil substances; they don't chew up normal cells; they just grow monotonously in an undifferentiated way taking up space and causing pressure on normal structures. What starts this process is a complicated chain of events at the molecular and biologic levels. Exactly what starts tumor cells to form and grow, we don't know, but we do know what doesn't cause tumors to grow. You don't get a brain tumor by eating the wrong foods, disobeying your family, or doing bad things. Some cancers, such as lung cancer, can be brought on by behaviors. If you smoke for 40 years, you can get lung cancer. Nothing like this occurs in brain tumors. The cause of brain tumors is actively being sought out by research scientist and this puzzle is being put together. But there is nothing that a family or child does to cause a brain tumor. Answered by Dr. Stewart Goldman, pediatric oncologist, Children's Memorial Hospital, Chicago July, 2007