Purpose.Approximately half of all radiotherapy (RT) is delivered with palliative intent. Clinical research in palliative RT aims to manage symptoms, improve quality of life (QoL), evaluate supportive care, and determine optimal dose-fractionation schedules. Our aim was to describe the prevalence of palliative research at the Canadian Association of Radiation Oncology (CARO) Annual Scienti c Meeting (ASM) over time. Methods. Published abstracts (2003-2021 were independently reviewed by two authors who categorized each as: curative-intent; palliative-intent; pertaining to both populations; or neither. Abstracts were considered palliative if they described incurable malignancy and interventions primarily for symptom control or QoL. Type of study, primary, site treated, and symptoms palliated were recorded. Descriptive and summary statistics were calculated including one-way ANOVA test for trend.Results. 339/4566 abstracts (7.4%, range 2.4-13.9% per year) were classi ed as palliative. 7.7% (26/339) described phase I-III trials. The main primary site was lung (39/339) and the most common metastatic site was bone (34.2%). QoL, symptom and toxicity outcomes were reported in 31.6% (107/339), 37.8% (128/339) and 17.7% (60/339), respectively. The most common symptom investigated was pain (38/339). The proportion of abstracts classi ed as curative, palliative or reporting toxicity endpoints demonstrated signi cant change over time (all p<0.0001).Conclusion. While proportion of palliative themed abstracts has increased with time, there remains a signi cant gap before equivalence with the prevalence of palliative RT in clinical practice is achieved.regarding palliative treatment of symptoms can be complex, requiring cost-bene t decision-making in the context of a limited life expectancy [5]. The choice of an optimal PRT regimen and management of disease-and treatment-related symptoms should be evidence-based whenever possible [8].Research is therefore essential to develop, re ne and disseminate the roles of RT (and ROs) in supportive cancer care [8,13]. Oncology conferences provide an opportunity to improve the collective body of knowledge, discuss research developments as well as provide continuing education [1,[13][14]. The breadth of data presented provides a window into a eld's research focus and current trajectory of inquiry [5]. Research is also important to increase consistency in working practices, and provide opportunities to apply positive outcomes from one setting to work in other settings [13]. However, despite the prevalence and importance of PRT delivery and RO involvement in routine supportive care, related research is infrequently reported at major conferences [1, 8,[14][15][16] or in high-pro le journals [5].The Canadian Association of Radiation Oncology (CARO) Annual Scienti c Meeting (ASM) provides opportunities to discuss new developments and disseminate knowledge to ROs and attendees from related disciplines. Our objective was to evaluate time-based trends in the number of palliative abstracts
