Prevalence of palliative radiotherapy abstracts presented at the annual scientific meetings of the Canadian Association of Radiation Oncology: 2003-2021.

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 Scientific Meeting (ASM) over time and compare this analysis to previously published work which evaluated the years 1992-2002.

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: Three hundred thirty-nine out of 4566 abstracts (7.4%, range 2.4-13.9% per year) were classified as palliative. 7.7% (26/339) described phase I-III trials. The main primary site was the lung (39/339) and the most common metastatic site was the 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 classified as curative, palliative or reporting toxicity endpoints demonstrated significant change over time (all p<0.0001).

Conclusion: While proportion of palliative themed abstracts has increased with time, there remains a significant gap before equivalence with the prevalence of palliative RT in clinical practice is achieved.