My mother succumbed to cancer over 10 years back. I was in my late teens and remember the treatment being way more painful than the cure. The medical care was so bad in india that once the nurse messed up the chemo shot and delivered it wrong. This resulted in oedema. Doctors could offer nothing more than an apology. I still find a lump in my throat when I recollect those days. However, in the end, my mother rejected treatment. She did however wish to live a long life. But she could not bear the treatment. Doctors gave her 2 months. But she lived on for 8 more months on painkillers to maintain as normal a life as possible. She managed to remain cheerful and positive before us kids. Living with someone you love knowing that they would die soon is really painful.
If I am terminally ill, I will probably reject treatment and choose to go peacefully.