Only 5 percent of terminally ill cancer patients reported having a complete understanding of their prognosis in a new study published in the Journal of Clinical Oncology.

Written by Holly Prigerson, PhD, of Weill Cornell Medical College and coauthors, the study was based on interviews with 178 patients expected to die within six months both before and after medical scans to restage their cancer were discussed.

Before the scans, only nine of those 178 correctly answered all questions about the understanding of their condition, a result which Prigerson said “astonished” her and her coauthors.

“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 in a statement. "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."

When patients were asked if they’ve had recent discussions about their life expectancy with oncologists, most gave one of two answers: 68 patients (38 percent) reported only having past discussions, while another 68 patients said they had never discussed prognosis. Eighteen patients (10 percent) reported only recent discussions of life expectancy, and 24 (13 percent) reported both recent and past discussions.

Without oncologists having those difficult conversations, Prigerson said patients can’t make informed decisions.

“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," she said. "That information may also help patients prioritize how they wish to spend the last few months of their lives, some by fulfilling bucket lists. Treatment choices patients make might follow from these priorities."

The study argued for oncologists to initiate these discussions with patients on an ongoing basis and as frequently as appropriate, which “may help patients and families who struggle to come to terms with the terminal nature of a disease.”