So, a PhD is like an MD without the fieldwork. And a PhD is like this:
http://matt.might.net/articles/phd-school-in-pictures/What that myopic, institutionally-granted dent in the universe gives you is the ability to write grants and manage student researchers for a living, but it's not necessarily going to help you solve cancer.
And let's say you go into the private sector as a bioinformaticist, that might get you somewhere, except private industry has nothing to gain from cures. A cured patient is a lost customer. The money is in abatement of symptoms and suffering for a monthly fee, and so that's what industry optimizes for.
What you, as an outsider, have, that people already there don't have, is the ability to cross disciplines. (Yes, ability. Talk to a PhD sometime. Most can't see outside their self-constructed walls until they've been out of academia for a few years, and they'll always have biases.) Academia doesn't like this, since it threatens each discipline's carefully drawn territorial boundaries. But you can do research like this: http://radar.oreilly.com/2012/03/data-science-deep-data-info...
Scroll down to the "Deep data" header and read that part in particular. There's a potential link between something and migraines, that's pretty much unexplored. Why? Because to advance in academia, your focus must be incredibly narrow. It is completely possible and likely that everyone everywhere has just missed it, because it's not some hugely popular or obvious micro-subject within the discipline. As an outsider, you can explore across different problem domains and different branches of medicine and potentially determine unexplored research avenues.
Gentlemen scientists and inventors of yore discovered new things regularly partially because there was plenty of low-hanging fruit to be discovered, but also because the big-S definitions of Science hadn't been codified yet, so they could pull from what would now be different disciplines without anyone rapping their knuckles with a ruler: http://interconnected.org/home/2011/03/17/finding_baby_scien...
Curing cancer -- which, while a multitude of diseases, comes down to magically identifying misbehaving cells and killing them -- isn't small-S citizen or gentleman science. It's royal, big-S science.
But, maybe the way you get there doesn't have to be.