Cancer treatment is so expensive, there are patients in the US who consider just giving up to save their families the trouble.
Imagine the worst case scenario, where the treatment fails and you die. On top of the emotional trauma, you also leave behind a very hefty medical bill for your loved ones to deal with.
On the other hand, it is also a very emotionally taxing feeling to know that your cancer might be bankrupting your family. Even if you have insurance, the final cost can still easily surpass 50,000$ which is just absurd. If you don't have insurance... good luck.
[Disclaimer: I never had cancer]