In most cases, doctors do not know the cause of brain cancer, though they do know that there are certain factors that can increase your risk. Knowing these factors can help you identify your risk and potential symptoms. The main risk factors for brain cancer include age, exposure to radiation, a family history of brain tumors, and currently having cancer that could metastasize, or spread, to your brain from another area of your body.
There is some evidence that nutritional habits during fetal development, during childhood and into adulthood may decrease your risk of developing brain cancer. Eating plenty of fruits and vegetables and lowering cholesterol may help you prevent brain cancer.
As a precaution it would be a good idea to use your cell phone only for short calls or texts, or use a hands-free device that keeps the phone—and the radio frequency energy it emits—away from your head. The point is more to preempt any risk than to protect against a proven danger: Evidence that cell phones increase brain cancer risk is "neither consistent nor conclusive," says the President’s Cancer Panel report. But a number of review studies suggest there's a link.
See your physician as often as he/she suggests