ESTRO 2025 - Abstract Book

S1781

Clinical – Upper GI

ESTRO 2025

Results: 57 clinicians responded, representing 40 centres.

For staging, 100% and 90% used PET-CT for oesophagus, GOJ Siewert Type 1 and 2 tumours, and GOJ Siewert 3 tumours respectively. 100% of responders had access to EUS, with 18% using routinely, 77% used selectively on a case-by-case basis and 5% not using at all. For TVD, total tumour length and total length of disease (LOD) was routinely reported on 66.7% and 36.8% of PET-CT reports and 61.4% and 26.3% of EUS reports respectively. 51% stated that their main use of EUS was to aid TVD, including LOD, proximal and distal margins of tumour and anatomical landmarks, but only 60% of responders stated that anatomical landmarks (e.g. aortic arch, carina and diaphragmatic crus) were included in their EUS reports

4% of responders reported TVD was undertaken in consultation with a radiologist. For 68% the radiology input in TVD was limited to the discussions that took place in MDT.

Conclusion: PET-CT is the most widely used modality for staging and TVD, but routine reporting of LOD is not universal. 50% used EUS to aid TVD, but information regarding LOD and position of tumour in relation to anatomical landmarks was again often absent. LOD is an important variable in determining if RT is feasible and may impact on eligibility for trial entry and would ideally be routinely reported on both modalities. Significant differences between PET and EUS LODs have been shown by Foley et al (2017), with PET tending to under-estimate LOD compared with EUS. The impact of these differences on patient outcome are being explored in the UK VALUE study. While use of EUS is lower than PET-CT, it was available in all centres represented. Further guidance on the benefits and indications for EUS may help to increase its use. PET-CT is widely used for staging and aiding TVD in OG cancers. EUS is widely available but its use is much more limited. For both modalities, key information that might aid treatment decisions and TVD are not routinely reported. A standardized reporting template for PET-CT and EUS would address this and could lead to improved TVD and resulting patient outcomes.

Keywords: EUS, PET, Outlining

References: 1. Foley, K.G., Morgan, C.A., Roberts, S.A., Crosby, T. (2017). Impact of Positron Emission Tomography and Endoscopic Ultrasound on Treatment Planning in Patients with Oesophageal Cancer. Clin Oncol (R Coll Radiol). 2017 Nov;29(11):760-766 doi: 10.1016/j.clon.2017.07.014.

1898

Digital Poster Magnetic resonance imaging to define gross tumour volume for radiotherapy in patients with gastric adenocarcinoma: a scoping review Kieran G Foley 1,2 , Bernadette Coles 3 , Amy Case 4,5 , Owen Nicholas 5 , Sarah Gwynne 5 1 Clinical Radiology, Velindre Cancer Centre, Cardiff, United Kingdom. 2 Division of Cancer & Genetics, Cardiff University, Cardiff, United Kingdom. 3 University Library Service, Velindre Cancer Centre, Cardiff, United Kingdom. 4 Clinical Oncology, Velindre Cancer Centre, Cardiff, United Kingdom. 5 Clinical Oncology, South West Wales Cancer Centre, Swansea, United Kingdom Purpose/Objective: Studies investigating MRI in gastric cancer have focussed on diagnosis and staging to date (1,2). Radiotherapy is proposed as a viable treatment option for patients with inoperable disease to prevent and treat symptoms (3).