My answer is that I only want to help those who have a strong desire to live. If a person wants to die, that is their business. Those who want to live should have every opportunity to do so. Occasionally, a shallow thinking health professional says that medical treatments are the only thing that cure cancer. He does not want his patient confused with the idea that anything but his doctor can help treat him.
Mental attitude has nothing to do with it.
Furthermore, if the patient tries mental imagery and it doesn't help them, they will have a guilt complex and that attitude will hinder their recovery. When someone can explain spontaneous remission to me, I'll quit believing in lots of things. The head of a major cancer center, an outstanding oncologist, told me he strongly believes in, as he put it, the will to live. He had a very good personal friend admitted with advanced cancer. He believed she had only a week or so to live.