Hey JKander welcome.
Part of my job involves teaching Critical Thinking and Logic classes at a university. I happen to have just gone over this kind of thing just within the past month. Not cancer/cannabis specifically, but the issue of personal experience vs scientific research.
The thing about your experience (and I don’t mean to single you out, I mean everyone here) is that your brain is designed to bias you toward conclusions that you like. (Or if it’s wrong to say it’s “designed” that way, it is a fact that its structure causes this to happen. In all of us.) This means, among other things, that when you see successes that seem to support your theory, you remember them, and when you see failures that don’t seem to support your theory, you forget them. You mentioned above that it has seemed to you to almost always work. But your impression that it almost always works isn’t worth much (I don’t mean to judge you here “as a person,” rather, I’m saying you yourself shouldn’t trust your impressions here) because if you’ve encountered a lot of failures as well, you’ve tended to forget about them or downplay them in your mind. You have no idea that you’re doing this–it’s totally subconscious. But we know this is how people work, and so we know that we can’t take anyone’s impression that something always works very seriously–even when it’s our own impression.
Scientific methodologies are designed to get around these kinds of biases. They set research up in a way that makes sure that the information gained is available for everyone to objectively examine, that the information takes into account both successes and failures, that the information (to the extent possible) is about just a single variable and not a mess of variables with unclear relationships. And so on. These are methods that have been honed over hundreds of years, intended to counteract deceptive tendencies contained in our brains that have had millions of years to evolve.
It is not a judgment on you, your value as a person, or your sincerity or general trustworthiness, when I say that I can’t really take any of what you’re saying into account. You’re talking about something you want to be true, and you’re not reporting information gathered by any known objective method. This means it doesn’t really matter how much you’ve seen. No matter how many reports you have, none of it gives me, or anyone else, (or, really, even you) a good reason to believe anything, because the conclusions you draw from your information just don’t follow from that information. For your conclusions to follow, we would need not just more information but information of an entirely different kind. Information about what happens in double blind trials. Information about plausible causal mechanisms. Things like that.
What’s your goal here?