High-quality end-of-life cancer care requires oncologists to communicate effectively and patients/caregivers to be participatory. However, most communication interventions target either but not both. We aimed to pilot a potentially disseminable combined oncologist-patient/caregiver intervention to improve oncologist empathic responses, discussions of prognosis and goals of care, and patient/caregiver participation. We assessed its feasibility, acceptability, and preliminary efficacy. Between June 2018 and January 2019, we conducted a pilot 2-arm cluster trial in Singapore, randomly assigning 10 oncologists in a 1:1 ratio to receive the combined intervention or usual care. Intervention arm oncologists received online communication skills training, and their patients received a brief prompt sheet before consultations. We audio recorded consultations with 60 patients with stage IV solid malignancy and analyzed 30 in the postintervention phase. The study was not powered for statistical significance. Participation rates for oncologists and patients were 100% and 63%, respectively. All oncologists completed the online training within an average of 4.5 weeks; 73% of the patients selected at least 1 question in the prompt sheet. Compared with the control arm, intervention arm oncologists had more empathic responses in total (relative risk [RR], 1.66) and for every patient/caregiver negative emotion (RR, 2.01). Their consultations were more likely to involve discussions of prognosis (RR, 3.00) and goals of care, and their patients were more likely to ask a prognosis-related question (RR, 2.00; P > .05 for all). The combined oncologist-patient/caregiver intervention is feasible and acceptable and has the potential to improve communication within consultations.