"can you trust your doctor"
In my mind, it has always been more of a consideration of "can I trust the medical system", after the doctor. Let's say, Dr. tells me my blood work-up indicates an out of range number for white blood cells (it happened to me, 2005). The "out of range" was less than 10%. He scheduled an appointment with a blood specialist, without my knowledge, then his office called to tell me that, giving a date for a bone marrow biopsy. I concluded on my own, that an out of range reading that small, did not warrant a biopsy. Biopsies introduce their own slew of possible adverse effects, and I hate the thought of a 6-inch long needle, to boot! I called it off. 10 years later, here I am, still kickin'!
Beyond that, let's say you are told you have some form of cancer, a malignancy which presents no "mass", like leukemia. Pathologist looks over blood cells, proclaims there are malignant cells. Real serious stuff now. How many such cells? If few, your body is likely disposing of them. If many, treatment via chemo is indicated. Such treatment is often living hell. How about a second opinion, different pathologist who knows  nothing of your first encounter?
Impossible today. Your ID is contained in a national databank, perhaps more than one, linked to your SS #. It's the first thing consulted by a Dr., especially if he knows he is a "second opinion". You're sunk. They work in cahoots. If it happened to me, and this is just MY OPINION, you need not get upset and disagree volubly, if I had no symptoms present troubling me, I would avoid treatment. I did that in 2005.     imp