FILE - A nurse places chemotherapy medication on an intravenous stand at the Fox Chase Cancer Center in Philadelphia.
FILE - A nurse places chemotherapy medication on an intravenous stand at the Fox Chase Cancer Center in Philadelphia.

Only a tiny fraction of those diagnosed with terminal cancer are fully aware of their prognosis, according to a new study.

Writing in this week's Journal of Clinical Oncology, researchers from Weill Cornell Medicine say advanced cancer patients “remain unaware of basic information about their illness or its treatment.”

The small study involved 178 terminally ill patients with cancer, having only months left to live. The patients were interviewed and asked about their health status, including what stage their cancer was and how long they expected to live.

Only nine, or 5 percent, acknowledged having “end stage … incurable” cancer, the researchers found.

"We were astonished to learn that only 5 percent of this sample had sufficient knowledge about their illness to make informed decisions about their care," said study co-author Holly Prigerson of Weill Cornell Medicine. "These were people with highly lethal metastatic cancers that had progressed after at least one prior line of chemotherapy; their life expectancy was approximately four months from our interview," she said. "Many did not know that they were at the end stage of their illness, nor that their cancer was incurable. They were basically making treatment decisions in the dark."

The reasons for the disconnect may be that patients just don’t want to know and the difficulty oncologists have telling patients just how sick they are.

"Our point is a lot of them don’t want to know, but they need to know basic information about the disease and illness and treatment options," Prigerson told ABC News.

Regarding doctors telling their patients, she said it was difficult for doctors to make clear they’re offering treatment and not a cure and that they have months, not years, to live.

"The results of this study show that when advanced cancer patients reported having recently discussed their life expectancy with their oncologist, their illness understanding improved significantly," said Prigerson. "That information may also help patients prioritize how they wish to spend the last few months of their lives, some by fulfilling bucket lists [lists of things one wants to do while still alive]. Treatment choices patients make might follow from these priorities."

She told ABC that previous studies show that terminally ill patients who fully understand their condition fare just as well as those not given the full truth about their disease.