There are books out on the market about the general stages of dying - the fatigue, mental confusion, loss of appetite, increased sleeping. But each person is slightly different depending on where the cancer is located. My Dad had cancer all through his body and bones (lung cancer mets) and he went peacefully. He gradually slowed down, less alert, no appetite. There are other little things people tend to do near the end but not worth mentioning here since they are not pain related.
If you can arrange for hospice care, they can make the transition as peaceful as possible. A volunteer, chaplain and nurse come by every week to see how you're doing, how well controlled is any pain you're having. The volunteer (like my husband) stays with you to keep you company for 4 hours a week so family can run errands. You never have to be alone.
I do hope you have family and friends to share this vulnerable time with you.