Most patients with cancer lack the prognostic understanding necessary to make informed decisions. We tested the feasibility and acceptability of the Oncolo-GIST ("Giving Information Strategically and Transparently, GIST") intervention and explored its associations with patients' improved prognostic understanding. The Oncolo-GIST intervention distills prognostic discussions into easy-to-understand talking points. Patients with metastatic cancers that progressed on ≥1 line of chemotherapy and not expected to survive 12 months (n = 31) were recruited from October 2020 through November 2022. We compared patients who discussed their progressive scans with an oncologist trained in the GIST technique or not (i.e., usual care). A primary outcome was prognostic understanding (e.g., patients reporting a life-expectancy of months) assessed within a week of the scan discussion visit. Oncologists (n = 4) appeared receptive to the Oncolo-GIST intervention and scored nearly perfectly on post-training tests of material mastery after a < 2-h tutorial. Post-scan discussion visit, 100% of patients who met with an Oncolo-GIST-trained clinician understood that their cancer was considered incurable (a 31% improvement from pre-visit) compared with 91% of patients meeting with usual care oncologists (an 18% improvement); 33% of patients who met with an Oncolo-GIST-trained oncologist understood that they likely had months, not years, compared to 18% in the usual care group. No statistically significant differences emerged for these changes, nor for therapeutic alliance, anxiety, or depression scores between groups. Oncolo-GIST appears to be an easily learned approach to improve prognostic understanding that neither undermines therapeutic alliances nor increases patients' anxiety or depressive symptoms. Efficacy testing in a larger trial is warranted.