IntroductionOlder patients with cancer are less likely to express their treatment preferences than younger patients. Question prompt lists (QPLs) facilitate communication between patients and physicians. Geriatric assessment (GA) is recommended when older patients with cancer make treatment decisions. This study estimated the effect size of a shared decision-making (SDM) support program combining QPLs with GA in terms of patients' subjective evaluation of the SDM process for a future definitive randomized controlled trial. We also evaluated the number and quality of aging-related communication during consultations, and feasibility and acceptability of the study for exploratory purposes. Materials and MethodsThis is a pilot study with randomized allocation and blind evaluation. Patients aged 65 years or older at the National Cancer Center Hospital, Tokyo, Japan, scheduled to discuss the changes of their treatment, were randomly assigned in a 1:1 ratio to the SDM support program or usual care. This program consisted of 30–60 min of face-to-face coaching, with QPLs and GA provided before the coaching. As the primary endpoint, the decisional conflict scores given by the patients immediately after the consultation were compared between the two groups. For the secondary endpoints, the number and quality of aging-related communications during the consultations were assessed by evaluators (blinded) using audio-recordings. Adherence, burden, and usefulness were assessed for evaluating feasibility and acceptability of the SDM support program. ResultsForty patients were enrolled. All patients completed the GA questionnaire, for which 70% did not require any individual assistance. Answering the questionnaires took approximately 11 min. The decisional conflict scores were mean [standard deviation (SD)]: 19.3 [10.8] vs. 18.0 [11.1] (effect size: Cohen's d = 0.12) for the SDM support program and usual care groups, respectively. The number of aging-related communications during the consultation for the new treatment was higher in the SDM support program group than the usual care (mean [SD]: 3.3 [1.2] vs. 2.2 [1.5], effect size: cohen's d = 1.32). Patients felt that the SDM support program was useful but not burdensome or difficult. DiscussionThe SDM support program was considered useful and feasible for older patients and able to facilitate communication regarding aging-related concerns. Trial registration numberThe study protocol was registered on September 23, 2020, in the UMIN Clinical Trials Registry (UMIN000041867).