system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: In theory, how could cancer be cured permanently?

In abstract, what is the thing that should be done to cure cancer permanently?
gpt
We can kill cancer cells easily and killing all cancer cells is how cancer is cured. Problem is most methods tend to kill off normal cells as well, which is the problem. We have some methods of targeting cancer cells over normal cells (mostly) which are radiation and chemotherapy. We would need a toxin or substance of some sort which discriminates between cancer and normal cells for this to happen.

Edit: Just wanted to add that while there are many different types of cancer, they all share similarities. Cancer at its most basic is a group of cells that somehow has had it's ability to limit growth tampered with/turned off. This is the main difference we exploit with today's treatments of chemotherapy (drugs that combat all cell growth, very little cells actually multiply in the body), and radiation therapy (this causes mutations in DNA, due to cancer's rapid multiplication, they do not check all the failsafes against DNA mutations, normal cells are better at repairing DNA damage, and this is done in the hopes that the mutations will make it that the cancer cells cannot survive). But there still are many different cancers, so we something that would treat all cancer would have to target the similarities, so the rapid multiplication of cells.