I also have cancer and from what I have been reading the THC is better at shrinking tumors then the CBD. Even if you turn it into butter the THC will still be there and also the psychoactive part as well. Additionally drowsiness is a side effect of smoking or ingesting THC.
I have tryed many different types of Chemo to try to shrink my tumors and most are pure poison that do have terrible side effects. So if I get a little high or drowsy I feel that is much better then the side effects of chemo. A one to one ratio of THC and CBD is preferred but hard to achieve from one strain, The CBD actually reduces the psychoactive part of THC.
I grew the Gold Leaf strain and mix 1 oz into a brownie mix. Then I eat one brownie a couple of hours before bed.
Hope this helps