Nature article
I cannot find the exact article I had used for a philosophy assignment (surprisingly, I think it was for my Statistics course, which I opted for the Philosophy of Statistics course to fulfill that requirement), but that above article does seem to refer to the same study I previously wrote about.
Psilocybin isn't just helpful for cancer patients, it's beneficial for many medical problems, though mostly for mental disorders like depression.
There is a lot of good with the chemical, but the issue is the legality as well as the style of use. You have to have a strong mind or have a controlled environment; you can have a weak mind, but have to have the right environment/conditions to help push the experience in the right direction. A bad experience can be tough for someone who already has mental issues.
It's one of many drugs that play in what I like to refer to as the spirituality-sector of the brain. When you tap into that section of the brain, there is a lot of good that can come from it - it's the same area of the brain responsible for all the "benefits" of religion... I find religion disgusting, but it's one of many ways to tap into your brain's self-help region.