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

I understand that cancer happens when a cell reproduces incorrectly and then creates a tumor by reproducing out of control. But how does that kill people? In other words, how do you die of cancer?
gpt
The tumor cells interfere with the normal working of the organ.  They may also release hormones or other substances which they shouldn't be releasing.  Furthermore, the tumor may metastasize, or drift around spawning other tumors, which then interfere with other organs.  It all ends up screwing with the body's biochemical balance.