ESTRO 2023 - Abstract Book

S1096

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ESTRO 2023

Conclusion The audit confirmed our cancer centre follows the available national guidelines. Its clinical outcome is comparable with that of the NETTER-1 trial. Treatment was well tolerated, with most patients completing all treatment cycles. Further areas of sub-set analysis are underway. References: 1. Strosberg J.R., et al. (2021) 177Lu-Dotatate plus long-acting octreotide versus high dose long-acting octreotide in patients with midgut neuroendocrine tumours (NETTER-1): Final overall survival and long-term safety results from an open-label, randomised, controlled, phase 3 trial. Lancet Oncol. 2021;22:1752–1763. doi: 10.1016/S1470-2045(21)00572 6. 2. National Institute for Health and Care Excellence (NICE) (2018) Lutetium (177Lu) oxodotreotide for treating unresectable or metastatic neuroendocrine tumours. Technology appraisal guidance TA539. Available at: www.nice.org.uk/guidance/ta539 (Accessed 25 October 2022).

PO-1366 Inter-observer variation in GTV delineation of esophageal cancer on MR, CT and PET CT

A. Secerov Ermenc 1,2 , P. Peterlin 1 , F. Anderluh 1 , A. Jeromen Peressutti 1 , J. But Hadzic 1 , V. Velenik 1 , B. Segedin 1,2

1 Institute of Oncology, Division of Radiotherapy, Ljubljana, Slovenia; 2 University of Ljubljana, Faculty of Medicine, Ljubljana, Slovenia Purpose or Objective In the present study we investigated inter-observer variation in gross tumor volume (GTV) delineation of esophageal cancer on different imaging modalities – CT, PET CT and MR. Materials and Methods Twenty-three consecutive patients with esophageal cancer treated with preoperative or curative chemoradiotherapy were selected. All patients had CT, PET CT and MR imaging in treatment position prior to radiotherapy. Five experienced observers from our institution independently delineated GTV for the first thirteen patients on CT alone, PET CT, MR alone and with co-registered PET CT and MR (figure 1). Inter-observer agreement, expressed in generalized conformity index (CIgen) and mean volumes of GTV were calculated per patient and imaging modality.