Regarding cancer cells and radio-frequency ablation
I think you're referring to radio frequency or microwave ablation. It works by heating the tissues up with electromagnetic radiation, just like you'd use to microwave food, but it's heating you instead. Healthy cells have better repair mechanisms and survive these treatments better. Cancer cells tend to have poor repair ability and can be killed more easily. I've heard of injecting metal nanoparticles which collect in the tumor due to the enhanced permeability and retention (EPR) effect. The nanoparticles respond to the microwaves much more powerfully than cells do and get hotter, burning the tumor from the inside out.