There's no doubt that doctors would prefer to treat cancer as soon as they spot it, and it looks like nanotechnology might give them that chance. Researchers at the University of Leeds have successfully tested gold nanotubes that are useful for both imaging and destroying cancer cells.
Since the tubes absorb near-infrared light frequencies, which both generate heat and render human skin transparent, you only need to zap them with lasers of varying brightness to achieve multiple ends. You can use a relatively low brightness to reveal tumors, while high brightness will heat the tubes enough to kill nearby tumorous cells. The shape also has room for drugs, so you can deliver medicine at the same time.