ESTRO 2023 - Abstract Book

S356

Sunday 14 May 2023

ESTRO 2023

Results: In Group I, robust optimization resulted in improved robust CTV coverage in all plans (see table 1). In Group II, PTV coverage was omitted in favour of sparing OARs. Robust CTVe coverage was slightly reduced but kept above 98% in all plans. Reductions in NTCP due to robust planning are shown in Table 2. In both patient groups, all patients had reduced NTCPs for both dysphagia and xerostomia. Reductions were largest for dysphagia in Group II, with median reductions of 11.9% for Gr 2+ and 12.3% for Gr 3+.

Conclusion Conclusion: We proposed a new approach for incorporating robust planning in clinical VMAT plan generation for head-and- neck cancer. While obtaining clinically acceptable plans with robustness in CTV coverage, robust plans also had clinically relevant NTCP reductions, especially for dysphagia. References:

[1] Korevaar E.W. et al. Radiother Oncol. 2019;141:267–274. [2] Langendijk J.A. et al. Int J Part Ther. 2021;8(1):354–365.

OC-0452 Identification of syndromes from temporal evolution of symptoms in cervix cancer patients M. Pelizzola 1 , S. Spampinato 1 , S. Chopra 2 , R. Nout 3 , K. Kirchheiner 4 , K. Tanderup 1 1 Aarhus University Hospital, Danish Center for Particle Therapy, Aarhus, Denmark; 2 Tata Memorial Hospital, Department of Radiation Oncology, Mumbai, India; 3 Erasmus University Medical Center Rotterdam, Department of Radiation Oncology, Rotterdam, The Netherlands; 4 Medical University of Vienna, Department of Radiation Oncology, Vienna, Austria Purpose or Objective The aim of this study was to use factor analysis to identify sets of co-occurring symptoms over time in locally advanced cervix cancer patients, focusing particularly on multifactorial symptoms with a strong impact on quality of life (QoL). Materials and Methods The EMBRACE I study is a multicenter prospective observational study with 1416 patients enrolled from 2008 to 2015 in 24 centers. Information on treatment, morbidity and patient reported outcome (PRO) has been prospectively assessed regularly during follow-up (in median 48 months). Data on PRO, QoL, and physician-assessed morbidity were collected using the EORTC and CTCAE v.3, respectively. The correlation of symptoms was evaluated using factor analysis on both EORTC and CTCAE data with symptoms and follow- ups as observations. Factor analysis is a statistical method that extracts latent factors from clinically observed single symptoms, accounting for their correlations. The underlying factors represent clinical syndromes, which are groups of co- occurring symptoms. The higher the loadings of a factor on a symptom (length of bars in figures 1 and 2), the stronger the relationship between syndrome and symptom. Factor analysis was applied on the EORTC and CTCAE data in patients where follow-up was available for all symptoms and maximum 25% missing entries.