If you had cancer, or another potentially terminal illness, what criteria would you use to decide whether you wanted treatment?

A few years ago, my brother-in-law was diagnosed with cancer. He was 73 and made the choice to only have palliative care. He felt he had lived a good life, and didn’t want to spend months on treatments that would leave him weak, couldn’t guarantee him more time, and possibly feeling worse than he did with the disease.

He discussed this decision with my sister (his wife) and she supported him. She would have been there with him for every step no matter what he decided.

What choice would you make? What factors would help you decide?