ESTRO 2022 - Abstract Book

S112

Abstract book

ESTRO 2022

within a SC by addressing 1 or 2 symptoms and therefore alleviating the severity of other symptoms within that SC. This way, greater gains in a patients’ health-related quality of life (HRQoL) can be achieved and patient care can be simplified. The aims of this study are to identify (1) SC and their change over time in lung cancer patients undergoing radiotherapy (RT), (2) SC with the greatest impact on HRQoL, and (3) demographical, clinical and/or treatment-related predictors of SC. Materials and Methods Data were used from the REQUITE study: an international prospective cohort study including lung cancer patients receiving RT from 26 different hospitals and 8 countries. SC were identified based on patient-reported outcomes collected before RT(T1), at month 3(T2), and month 6(T3) after RT with the EORTC QLQ-C3O and the lung symptom questionnaire. A combination of the following machine learning techniques were used to identify symptom clusters at different time-points, to investigate the impact of the SC on HRQoL and to predict the SC, respectively: hierarchical agglomerative clustering, linear regression and random forest regression. To guarantee external validity of the prediction model, a first part of the data set was used to develop the prediction model, and a second part to validate the prediction model for unseen data. Results Data from 418, 341, and 299 lung cancer patients were analysed at T1, T2, and T3, respectively. Three SC were identified and remained stable over time: cluster 1 (fatigue, dyspnoea, physical and role functioning), cluster 2 (coughing blood, swallowing problems, nausea and diarrhoea), and cluster 3 (social, emotional and cognitive functioning). On T1 and T2, a 4th cluster was identified (general pain, chest pain and coughing). Cluster 1 was most common across all time points, followed by clusters 3, 4 and 2. At T1, cluster 3 had the greatest impact on overall HRQoL (34% explained variance) while cluster 1 had the greatest impact at T2 (39%) and T3 (50%). Two symptoms within cluster 1 (dyspnoea and physical functioning) could be moderately predicted at T2 with age and RT parameters (i.e. planned target volume, max. dose oesophagus and dose per fraction) being the greatest predictors. Conclusion Supportive care interventions for lung cancer patients undergoing RT must tackle 1 or 2 symptoms of the ‘fatigue, dyspnoea, physical and role functioning’ cluster because this SC is most common across time-points and has the greatest impact on the patients’ HRQoL. Furthermore, age and RT parameters should be taken into account to further tailor future interventions in lung cancer patients. P.K. Møller 1 , L. Dysager 1 , U. Bernchou 2 , A.S. Bertelsen 2 , C. Brink 3 , F. Mahmood 2 , H.R. Jensen 2 , O. Hansen 1 , C.J. Nyborg 1 , H. Pappot 4 , K.B. Dieperink 1 1 Odense University Hospital, Department of Oncology, Odense C, Denmark; 2 Odense University Hospital, Laboratory of Radiation Physics, Odense C, Denmark; 3 Odense University Hospital , Laboratory of Radiation Physics, Odense C, Denmark; 4 Rigshospitalet, Department of Oncology, Copenhagen, Denmark Purpose or Objective The study Prostate Radiotherapy Integrated with simultaneous MRI (PRISM-OUH) was initiated to assess feasibility and tolerability of online adaptive radiotherapy on the 1.5 T MR-linac (oMRgRT) for patients with localized prostate cancer (intermediate risk). To achieve the complete picture of tolerability, the aim of the present study was to describe the development in patient-reported outcomes (PROs) over a six months period following oMRgRT. Materials and Methods For patients with prostate cancer, oMRgRT was delivered in 20 fractions with daily online adaptation. Radiotherapy (RT) was planned to a total dose of 60 Gy in the prostate and proximal 1 cm of the seminal vesicles (SV), and 48 Gy to an additional 1 cm of the SV . PTV margins were 5 mm isotropic, except for 3 mm posteriorly for PTV 60 Gy. To assess patient symptoms and HRQoL, the patients reported the International Prostate Patient Index (I-PSS, lower score=lower symptom burden) and the Expanded Prostate Cancer Index (EPIC-26, higher score=better HRQoL) at baseline, end of RT, and one, three and six months after end of RT. In addition, HRQoL was assessed with the EUROQOL EQ-5D-5L (1=max HRQoL) at the same time points. Results In total, 31 patients were included; median age 69 (46-76), Gleason score 6 (n=4) and 7 (n=27), 78% had ECOG/WHO performance status 0, and 48% received six months of LHRH agonists. Out of 620 planned treatment fractions, 26 were delivered on a CT-based linac (15 to one patient finding the treatment time hard to tolerate, 11 due to technical problems). Moderate/severe urinary symptoms was reported by 74% of the patients at the end of RT (highest mean I-PSS score 13.6). This score was still above the pre-treatment level (6.5) one month following RT (11.3). Three months following RT, the same proportion of patients with moderate/severe urinary symptoms as pre-treatment (30%) was obtained (Table 1). These findings were consolidated in the EPIC-26 domain scores. In three domains (urinary incontinence, urinary irritative /obstructive and sexual), the pre-treatment summary score was not reached until three months following RT (Table 2). Pain or burning on urination was one of the symptoms worsened one month after RT (15% vs 3% baseline). Patient satisfaction with their urinary condition reached the pre-treatment level one month after RT (Table 1). The HRQoL of the patients was stable throughout oMRgRT (EQ index score 0.907) and improved one and three months following RT (0.911-0.951). OC-0136 Acute toxicity reported by patients with prostate cancer receiving online MR-guided radiotherapy

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