First, let's define terms. Good question when facing a terminal illness. I quote Dr. Ron Sloan, in my book Part of my practice in helping people die, as well as helping people live. I don't put people on medications I know won't help them. I don't put people on ventilators who aren't doing to be helped by them.
Assisted suicide is very different.
He provides all the means for death, but the suicidal person actually turns on the gas or triggers the delivery of deadly drugs. One person does something that directly kills another. For example, a doctor gives a lethal injection to the patient. For today, I'm going to lump both together and refer to them both as euthanasia. Both intentionally make people die, rather than allowing them to die naturally.