Honey is made by bees. Bees collect nectar, and carry it back to the hive. They regurgitate the nectar into the cells of the honeycomb. They beat their wings to dry the nectar and excrete saliva into it. Their saliva contains enzymes that alter the nectar. Ultimately, what results is honey which possesses antibacterial properties - meaning that bacteria cannot survive in it.
The question for cancer patients is: Does honey help against oral mucositis? I'll try to compile some relevant links to build a case for that.