My son has leukemia, and I would never get him a joint to smoke, much less light it!
There's nothing more hilarious than potheads arguing about the wonders of their wonder drug, "medicinal" marijuana. They crack me up. ROTFLMAO!
I know nothing about your son's situation, but I was discussing my father's situation. He was DX with pancreatic cancer when he was 68 years old. That's plenty old enough to decide what to put into your own body. (He never did express any interest in MJ even though he went through hell with surgery and chemo) And although I've never used illegal drugs I would have gotten whatever he may have asked me to, somehow.