Question

If neurons can't multiply then how does brain cancer occur?

Answer 1

 You are right
cancer is due to rapid division of cells, that neurons don't usually divide after the brain forms, and that the brain has more cell types than just neuron They can become cancercells.

Answer 2

The brain tumor occurs when some neuron damaging viruses enter your body. They automatically straight go to the brain where they start their process of making neurons and cells into larger viruses and bacteria. That is how the brain cancer occurs.

HOPE IT HELPS!!