A friend of mine has been living well with lung cancer for five years — working, running several miles a day, traveling, doing good stuff with his family, and generally enjoying the pleasures of everyday life. He knows the cancer will eventually kill him, but has been making the most of every remaining minute.

Then, a month ago, things suddenly turned dramatically south. Severe shortness of breath, constant coughing, sleeplessness, fatigue, loss of interest, anxiety. My friend figured the jig was finally up — that he was going terminal. We all felt sad in the face of this inevitability. In our different ways, we began the painful process of saying goodbye.

Then things seemed to get even worse. I accompanied my friend to visit his lung doctor — an amiable and thorough man who spent lots of time with us, took a good history, and did many tests.

We gazed expectantly as the doctor came back into the consulting room and began gravely summarizing his findings. He brought what seemed to be terrible news: “I am really worried about you. Your oxygen saturation has dropped below 90 and your breathing is suddenly getting much worse. This kind of sudden deterioration can be caused by one of four things — pneumonitis from your previous radiation treatment, pulmonary embolism, pericarditis, or infection.”

My friend had been as low as I could imagine before the visit. But now his face went white, his mouth sagged, he began to tear, and the shortness of breath and cough became more palpable. Death seemed about to suffocate him.

“Wait a minute, doc,” I said. “I don’t understand. How about the cancer? Are you saying the cough and reduced oxygen are not caused by the cancer.”

“Right. I checked all the scans and the cancer hasn’t changed at all. It can’t be causing this.”

“And how treatable are these four new possible causes?”

“Very. We have to do some more tests to figure out which it is. Probably pneumonitis and that’s easy to treat with low dose prednisone. The other things are also very treatable. My guess is that the cough and shortness of breath should be OK in a week or two.”

With a new lease on life, my friend returned quickly from death’s door. The transformation was immediate and unmistakable — I have never seen a human being change demeanor so fast. Face filled with joy, he thanked the doctor for inspiring such confidence. There was a renewed bounce to his step as we left the office that I had never expected to see again.

And even more remarkable, my friend’s cough and shortness of breath began improving almost at once. There is a strange healing power in a doctor’s words that has allowed doctors to be useful over the millennia even when their treatments were ineffective or harmful. Reduced fear and renewed hope are wonderful medicines.

The doctor had certainly done a lot of things very right — spending substantial time with his patient, doing a careful evaluation, and that final guarantee of success.

But the doctor had done one thing that was incredibly stupid. He should have entered the room with a bright smile and said something like: “Congratulations. Great news: It’s not your cancer causing these new problems. There are four different possible explanations. With a few more tests, we can figure out which one is responsible and you should be feeling much better within a couple of weeks.”

How could a smart and caring doctor say such a dumb thing to so vulnerable a patient? Simple. We overtrain our doctors on the overvalued technical aspects of medicine and under-train them in the undervalued relational skills that have always been at the heart of healing.

Allen Frances is a psychiatrist and professor emeritus, Duke University.  He blogs at the Huffington Post.