This question already has an answer here:
This says he doesn't
This says he might
I think this one is the main claim
The title says:
Trevor Smith's Story: How he Beat Bladder Cancer Naturally with Cannabis Oil
I tried to look for more info about Trevor Smith but can't find it.
Again, none of the source is credible. One is forum posts. Another is 9gag. Another seems like a commercial website promoting that guy.
And that's the thing. I can't find any credible source talking about it. It looks notable. Yet, I don't know it's true or not.