What are the causes?

The exact cause of tumours is not known. However, there is a higher risk of tumours in:
Children and elderly
People with certain rare congenital abnormalities like Li-Fraumeni syndrome, tuberous sclerosis etc.
People with disorders of the immune system or auto-immune disorders like AIDS
People who are exposed to X-rays of the head
People who work in certain industries like oil refining, drug and rubber manufacturing.