My Mom Has Been Fighting Acute Leukemia For 3 Years.

My mom has been fighting acute leukemia for 3 years. 2 months of chemo did no good, her blast cells still too high. Anyway for the past year she has been getting blood transfusions every 3-4 weeks. She also has severe rehumatoid arthritis. She is in so much pain and has very little energy. She is 68. She has just announced to the family that she doesn't want anymore blood tests or transfusions. She is ready to go. I read in an article that someone can live with their red blood count in the 40's. She always gets transfusions when hers dips into the 70's. I also read that some patients get transfusions several times a week. She wasn't at that stage. I know that no one can predict life expectancy but I was wondering how long she can last without transfusions and how will her body start to shut down.