Hi, the amount of curvature is generally the most important thing. Sometimes the therapy is a brace. Otherwise a big surgery is required. Sorry to say, it most likely won't get better on its own, but will get worse over time.
But you can find reports of people doing specific exercises to make it better.
Just going from memory, 12 degrees isn't too bad.
I'd also look into how rapidly it developed. If very suddenly, then this is important: I'd want to look into the possibility of a syrinx and/or Chiari malformation.
You really need to find a scoliosis group,
From what I could gather online, dextroscoliosis is a curvature of the spine. I don't think it has anything to do with cancer, more like an incidental finding on the xray. 12 degrees must mean how far it is curving. I don't know how serious this is, but I would mention it to your doctor when you go over the results just to make sure it's nothing to worry about.