After reading so many stories on this site I realise every case is different. I will share my story about my dad:
He was diagnosed with prostate cancer in January 2012. Doctors assured him it didnt spread to the bones or other organs.
In March they started with precautionary radiation treatment around the prostate area to prevent the cancer for spreading. He had 5 treatments after which he became ill very suddenly - mostly exhaustion and signs of depression. His doctor told him this is normal for cancer patients in the early stages of radiation.
Days went by and he started to have no appetite, yellowness of the skin appear and he lost weight rapidly.
On 10 April this year he was admitted to hospital as both he and my mom realised something is really wrong.
He was diagnosed on 12 April with advanced and aggressive liver cancer and died the morning of 15 April.
He didnt have much pain until his last day when they started with morphien treatment.
It was so suddenly and still a great shock for us all but at least I rest assure that he didnt have much pain. I have heard stories about liver cancer and the pain patients have to go through until the end.