Though it is very difficult to find out the root causes behind the occurrence of Brain Tumors, there surely are some risk factors like:
Family History
Exposure to ionizing radiation like undergoing Radiation Therapy

The symptoms of this medical condition about which the patients should be made aware, are:
Headaches
Seizures or convulsions
Nausea or vomiting
Any changes in vision
Difficulties in speech
Inability of concentrate
Numbness or tingling sensation in the arms or legs
Loss of motor skills like weak movement or balance, loss of coordination, etc.

Cancers have a reason to occur now?