It is a brain cancer located right behind the ear.
I am convinced that it is caused by holding cell phones against your ear for long periods of time, in other words people who talk on their cell phones a lot are the most likely to get it.
Unlikely once you understand the science. You need high energy, ionizing, radiation to cause cancer. It needs to carry enough energy rip electrons from their atoms. Gamma rays, x-rays, UV-C and some UV-B can do this. Below that there isn't enough energy carried to damage an atom: visible light, microwaves, and even less energy in the RF waves from a cell phone.
So maybe there is some mechanism we don't understand yet, but there is neither empirical evidence to support the effect, nor is there a scientific reason to think it would. 
“holding cell phones against your ear”
So use speaker whenever you can.
“It is a brain cancer located right behind the ear.”
Glioblastoma can occur in many locations of the brain, not just behind the ear. It most commonly occurs in the cerebral hemispheres, particularly in the frontal and temporal lobes, but it can develop in other regions of the brain as well.
Is this the type of cancer Johnny Vicran had? His family said it was from using his phone.
Agreed on “cell phones” for sure
I try to use speaker feature of cell phone.
100% nonsense. Glioblastoma can occur anywhere in the brain. And there have been all kinds of studies showing no link between brain cancers and cell phones. I have a type of brain cancer 1 grade below glioblastoma. I hardly ever talk on my cell and when I do it’s almost always on speaker. It’s pure chance.
A beloved relative died of glioblastoma more than 30 years ago, long before cell phones were around. It is a horrible disease. Eight months from diagnosis to death.