@pastanaga - The two are related, you're right. Red light therapy is a slightly less intense version of the intense pulsed light therapy you probably had for hair removal.
It's used for quite a few things, not just for removing throat cancer. But I think it's still considered a bit controversial at the moment.
While it's undeniable that it does work with some things, with others, like pain relief, it's not quite as clear cut.