S1520
Interdisciplinary - Quality assurance and risk management
ESTRO 2026
Sydney, Australia. 4 Medical Physics, Liverpool and Macarthur Cancer Therapy Centre,, Sydney, Australia. 5 Research and Quality Assurance, Trans-Tasman Radiation Oncology Group, University of Newcastle, Newcastle, Australia. 6 Cancer Care Services, Sunshine Coast University Hospital, Birtinya, Australia. 7 Radiation Oncology, CancerCare Manitoba, Winnipeg, Canada. 8 Radiation Oncology, UZ Leuven Cancer Institute, Leuven, Belgium. 9 Medical Imaging and Radiation Sciences, Monash University, Melbourne, Australia. 10 Radiation Oncology, North West Cancer Centre, Tamworth, Australia. 11 Radiation Oncology, Princess Margaret Cancer Centre, Toronto, Canada. 12 Radiation Oncology, Hospital Universitari Vall d’Hebron, Barcelona, Spain. 13 Radiation Oncology, Liverpool and Macarthur Cancer Therapy Centre, Sydney, Australia Purpose/Objective: TOPGEAR, a phase III trial in resectable gastric cancer, demonstrated no survival advantage with the addition of preoperative chemoradiotherapy (CRT) to peri- operative chemotherapy.1 Owing to the complexity of gastric irradiation, a prospective RTQA programme was incorporated into the trial.2 Following trial completion, we conducted a retrospective secondary analysis to examine whether RTQA participation and contour quality based on clinical protocol compliance, were associated with clinical outcomes. Material/Methods: Among 286 patients randomised to receive CRT, 202 patients (71%) underwent prospective pre-treatment RTQA and 84 patients (29%) did not.Following trial completion, a secondary expert review of available clinical target volume (CTV) contours (n=219) was undertaken using the same protocol definitions to provide an idealised post-trial ‘gold-standard’ assessment independent of clinical workflow constraints.Each case was reclassified as pass or violation based on this secondary review. Clinical outcomes (OS, PFS and grade ≥ 3 toxicity) were compared between RTQA-pass and violation groups for both the initial and secondary reviews using Kaplan–Meier, log-rank, cox-regression and chi- squared tests. Results: Median OS was 50.6 months for RTQA-reviewed and 37.8months for non-RTQA (Hazard Ratio (HR)=0.79; 95% CI:0.56-1.12; p=0.18; Figure 1). Median PFS was 34.9months versus 22.2months (HR=0.74; 95% CI:0.53- 1.04; p=0.079; Figure 2).Post-trial ‘gold-standard’ review of 219 cases identified 164 (75%) passes and 55 (25%) violations. For these, median OS was 50.6 vs 30.1months (HR=0.82; 95% CI:0.55-1.23; p=0.33) and median PFS 34.4 vs 21.6months (HR=0.83; 95% CI:0.56- 1.24; p=0.37). No significant differences were seen in grade ≥ 3 toxicity (67% vs 69%; p=0.78). A sensitivity
Of the final contours reviewed, 1628/1665 (98%) target contours and 3724/3749 (99%) OAR contours were graded as acceptable-per-protocol or acceptable variation, compared to 1499/1665 (90%) targets and 3617/3749 (96%) OAR contours at initial review.Of 298 contours initially recommended for revision, 79% (236) were amended following prospective review feedback. For the remaining 62 contours, mitigating reasons for not correcting were available for 37. Evaluation of dosimetric impact for the remaining 25 contours showed no effect on optimal or mandatory trial dose constraints in all but two cases. In one case, CTV2 and CTV2n did not meet the D99 target, although the D95 target was achieved. In another, the corrected oesophagus contour received 2 Gy above the optimal mean dose of 20 Gy. Conclusion: Real-time QA ensured 99% contour compliance with the protocol at treatment. The study findings underscore the need to better understand and quantify how contour variation impacts on trial dose constraints.As the first UK proton-photon trial with a primary objective to understand potential reduction of side effects, strict adherence to the radiotherapy guidelines ensured valid comparisons between treatment modalities. The robust RTQA programme effectively identified and corrected contours that did not fully conform to protocol. Keywords: Contouring Radiotherapy Quality Assurance and Clinical Outcomes: Secondary Review Findings from the AGITG TOPGEAR Phase III Trial Karen L Olden 1 , Trevor Leong 1 , Rachel L O'Connell 2 , Phillip Chlap 3,4 , Lois Holloway 3,4 , Alisha J Moore 5 , David Willis 6 , Mohamed Akra 7 , Eszter Hortobagyi 8 , John Ryan 9 , Katelyn Wall 10 , Rebecca K S Wong 11 , Jolie Ringash 11 , Begoña Navalpotro 12 , Karin Haustermans 8 , Jelena Lukovic 11 , Mark T Lee 13 1 Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia. 2 Clinical Trials Centre, University of Sydney, Sydney, Australia. 3 Medical Physics, UNSW and Ingham Institute for Applied Medical Research,, Proffered Paper 2644
Made with FlippingBook - Share PDF online