I was thinking this'll actually become the most effective treatment for cancer, myself.
The problem with a "cure for cancer" is that every cancer is unique (probably, statics say there'll be duplicates here and there, but only after millions of cases).
Meaning one would have to tailor a genetic modification-based cure for each cancer, regardless of delivery methodology.
Until genetic modification becomes common place, it's likely to be incredibly costly, even if it's more effective (of which there is no guarantee).
In fact, I'd venture to say that a "cure" for cancer may actually be nothing but a pipe dream for centuries. Better to find more effective treatment and removal methods.