When should the Dr. tell the patient how long they have to live?

My dear friend has been diagnosed with stage 4 Pancreatic Cancer. She has wasted to 88 pounds. She is no longer able to eat or take in fluids. She went into the hospital and had IV's, a stint in her bile duct and the Dr. suggested she try to eat. Her pain level is severe. She is on Morphine suppositories an a patch. She thinks if she goes to Houston, she can be cured. She is in denial, I want to be there for her and I will be, but don't know if she should know that she only has weeks left to live. I don't want what is left of her life spent trying to find a cure that isn't there. I am feeling so very helpless.