Well there are two possibilities I can see, both admittedly rather rare:
- There are several rare curable diseases, but aren't properly treated due to the expense of treatment. The medicine isn't in demand enough to mass produce it. I see these brought up every once in a while as a criticism for profit based healthcare.
- It doesn't seem to far fetched to me to come up with alternative treatments that are effective, but not as effective, that are pushed aside as completely irrelevant because they can't be monetized as well. I'm pretty sure most doctors would push the most effective treatments unless they're prohibitively expensive, but lesser ones that a cheaper might be ignored. This is conjecture on my part, so could very well be wrong.
These points do make sense, but neither case would generally involve alternative medicine as far as I can tell. The first case is a nasty dilemma about how much money you're prepared to pay per person (ultimately you have to set a limit, unfortunately). I can imagine something like the second case arising through patents (big pharma pushing their own patented drugs over the cheaper "generic" drugs they no longer hold the patent on) but that case only really works if both drugs have already been shown to work.
It's also something that should be addressed in Ben Goldacre's new book, which I need to get a hold of and read as soon as possible.