2958 - Early Outcomes and Implementation of Online Adaptive Radiotherapy for Long-Course Fractionated Treatments: A Systematic Review
Presenter(s)
L. Burns1,2, A. Salkini3, H. Chen1,4, A. H. Safavi1,2, M. C. Tjong1,2, and A. V. Louie1,2; 1Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada, 2Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, ON, Canada, 3MD Program, University of Toronto, Toronto, ON, Canada, 4Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
Purpose/Objective(s): Online adaptive radiotherapy (oART) may improve target coverage and reduce normal tissue toxicity by regularly accounting for interfractional volume changes during long-course fractionated treatments. While promising, oART is resource intensive and initial adoption has focused on stereotactic and hypofractionated settings. We summarize the early outcomes and implementation of long-course fractionated oART.
Materials/Methods: This systematic review was conducted according to the PRISMA guidelines, where Embase and Ovid MEDLINE databases were queried from 2010 to 2025. Studies were screened independently by two reviewers and were included for data abstraction if >3 patients were treated with >15 fractions of radiotherapy, using MR or CT-guided oART technology. Exclusion criteria included particle therapy and planning studies without patients receiving oART. Outcomes of interest include disease site treated, session time, frequency of online adaptation (daily, weekly, or on-demand), and clinical outcomes.
Results: From 1020 search results, 102 articles met inclusion criteria. Of these, 63 employed CT-guided oART and 39 MR-guided oART. Manuscripts originated (based on first author demographics) from 49 distinct institutions, across 16 countries; two articles reported multi-institutional studies. A median of 10 patients per article (range 4-157) were treated with fractionated oART among 92 articles where exact patient subgroup counts are reported. When reported for a single disease site, fractionated oART was most commonly described for prostate (n=23), followed by gynecologic (n=20), bladder (n=9), head and neck (n=8), esophagus (n=5), and other sites (n=14). Twenty-three articles reported fractionated oART for multiple disease sites.
Clinical outcomes were reported in 28 articles (CT n=16, MR n=12), including oncologic (3/16 CT, 1/12 MR), toxicity (13/16 CT, 10/12 MR), and patient experience (3/16 CT, 3/12 MR) endpoints. Four studies reporting clinical outcomes (3/16, 1/12) compared oART with non-oART approaches either prospectively (n=2) or retrospectively (n=2). The remaining 74 articles exclusively report dosimetry and/or technical workflows. oART adaptation frequency was reported as either daily (CT n=58, MR n=35), weekly (MR n=1), or on-demand (CT n=3). Three CT-based studies reported using multiple adaptation frequencies within each article, and frequency was not specified for two MR-based articles. Median total oART time per fraction was 30 minutes for CT-guided (n=32, range 18-58) and 38 minutes for MR-guided (n=22, range 19-57).Conclusion: This systematic review reports substantial heterogeneity in the worldwide development and implementation of oART for fractionated treatments. Prospective studies are needed to define optimal workflows and assess the clinical impact of these technologies.