The cause cancer or brain tumors can not be ascertained. Doctors can seldom explain why one person develops a brain tumor and not with others.
Causes of brain cancer is a major topic for researchers as well as other cancers. There are times when certain genetic conditions and exposure to radiation head (which is received during radiotherapy as part of the treatment of other conditions) are known to cause cancer.
There are several studies showing the possibility that the cause was a brain tumor cell phone. But this is not a definitive conclusion and does not really exist in a very convincing theory about what causes brain cancer.