Comment by maxdo

It's not.

The key thing is, one of the things most tumors need to do to get past a certain point is avoid getting caught being tumors.

If you can very selectively cause precise tissue death, from any method, then your body will suddenly start looking askance at any tissue that looks like the secretly-full-of-tumor-markers corpse it just found.

And ultrasonic cavitation means you can, in theory, cause very precise tissue death with even less surrounding effect than radiation.