mRNA based stuff is indeed incredible, no more randomly just trying things out, it's really the future IMO.
But for cancer it will just be a tool in the toolbox , I mean you gotta get those samples and cancer change maybe a thousand times a minute, which strain is the "bad" one? Etc. etc. etc.
One theoretical way to stop cancer altogether would be to remove the possibility for telomere lengthening (remove the production of telomerase) and "manually" allow the growth of only stem cell from time to time.
But that's a long time from now if ever it can be done.