A study of cancer patients and their doctors in the Annals of Internal Medicine a year later found that many doctors didn’t quite tell patients the truth about their prognosis. Doctors were up front about their patients’ estimated survival 37 percent of the time; refused to give any estimate 23 percent of the time; and told patients something else 40 percent of the time. Around 70 percent of the discrepant estimates were overly optimistic.

This optimism is far from harmless. It drives doctors to endorse treatments that most likely won’t save patients’ lives, but may cause them unnecessary suffering and inch their families toward medical bankruptcy.

One source of this optimism is pop culture, which frequently depicts heroic recoveries from seemingly life-threatening situations. Another is the medical school experience. What motivates weary medical students is the hope that one day interventions they perform will save lives, heal families and enact cosmic good.

Later, our judgment becomes clouded as we build relationships with patients, share their fears and anxieties, cherish their small victories and celebrations and hope that there may still be a way, however unlikely, they can make it to their grandson’s bar mitzvah.

And yet studies have shown that patients almost universally prefer to be told the truth. If physicians cannot deliver the hard facts, not only do they deprive their patients of crucial information, but they also delay the conversation about introducing palliative care.