Can I expect my doctor to tell the truth about my illness?

Doctors in the U.S. tell the full truth of the diagnosis and prognosis, no matter how positive or negative it is. It's part of our creed here in the U.S.—while in some other countries this info may be withheld from patients (and patients know this, which is why there is great distrust).

Without a doubt, it can be difficult to give a patient bad news and still have them respect you and believe you're doing your ultimate best to help them. Some patients do hold a bad diagnosis against their doctor, and then they shop for a second opinion not to increase the accuracy of their diagnosis, but simply to hear the news that they want to hear from a doctor (or alternative medicine practitioner) who will willingly contradict their first physician. And guess what? If they ask enough doctors and practitioners, they'll find someone who will tell them exactly what they want to hear, whether it's true or ethical or dangerous or not.