system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How exactly does cancer kill?

Obviously cancer is bad, but I never understood how exactly it kills.
gpt
When people get cancer, it affects certain organs. How bad the cancer is depends on what organ it's growing on (although, no cancer is good). Things get really bad when the cancer *metastasizes*, that's when it spreads to a different organ.

When an organ has cancer, it's like it's carrying around a 50 pound backpack full of stuff it doesn't need and it gets tired really easily. There comes a point when the organ is so tired it's not going to work at all. When this happens to an organ that you need to survive, you die.