You can use pure CBD products, they're much MUCH less effective than CBD with 3% THC in them. I wrote an article on the subject here: Considering a Pure CBD Product? Why Full Plant Cannabis is Massively More Effective

Now, for cancer patients in non-medical states, I would combine a CBD product with choosing alkaline foods for your blood type. You can also look into baking soda and blackstrap molasses for pH control, until your system is alkaline enough from foods.

Cancer does not thrive in an alkaline body, making it much easier to get rid of.