ESTRO 2020 Abstract book

S598 ESTRO 2020

SCF and contralateral SCF. There is no randomisation to the dose escalation arm of GTVn in SCOPE 2 so CTVscf is treated to 5000cGy in 25#.

Among the 35 pancreatic carcinoma patients treated with definitive RT, 23 patients were included in this study. There were 11 male and 12 female, with a median age of 66 (range, 38-86) years. 20 patients had a PS score of 0 or 1, 3 patients had a PS score of 2. One was diagnosed with clinical stage IB disease, 1 with clinical stage IIA disease, 3 with clinical stage IIB disease, 18 with clinical stage IIIB disease. 13 tumors were located in the head or uncus of pancreas and 10 tumors were located body or tail of pancreas. The median tumor diameter was 30 mm (range, 20-100 mm), and the median CA19-9 levels before RT was 216 U/mL (range, 1.2-26751 U/mL). The median prescription dose was 50.4 Gy (range, 45-64.8 Gy/15-36 fr), and the median V30Gy, V40Gy, V45Gy, V50Gy, mean dose of normal pancreas were 36.8%, 62.0%, 69.3%, 78.0%, 43.2 Gy, respectively. The median serum AMY levels before RT was 60 U/L (range, 39-290 U/L). The median follow-up time was 13.7 months, and AMY deficiency was observed in 13 patients during the follow-up period. The median time of AMY deficiency free probability was 13.3 months. There were no statistically significant factors influencing on AMY deficiency free probability including dose volume index. Conclusion Among patients with pancreatic carcinoma, AMY deficiency was observed about one year after RT and we should be careful about patients’ nutritional status around that time. There were no significant correlations between AMY deficiency and irradiated dose to pancreas. PO-1037 A new nodal delineation protocol for upper third oesophageal cancers in the SCOPE 2 trial O. Nicholas 1 , G. Radhakrishna 2 , R. Banner 1 , S. Mukherjee 3 , M. Hawkins 4 , T. Crosby 5 , S.H. Gwynne 1 1 Swansea Bay University Health Board, South West Wales Cancer Centre, Swansea, United Kingdom ; 2 The Christie NHS Foundation Trust, Department of Oncology, Manchester, United Kingdom ; 3 CRUK MRC Oxford Institute for Radiation Oncology Gray Laboratories- Oxford University, Department of Oncology, Oxford, United Kingdom ; 4 University College London Hospitals NHS Foundation Trust, Department of Oncology, London, United Kingdom ; 5 Velindre University NHS Trust, Velindre Cancer Centre, Cardiff, United Kingdom Purpose or Objective SCOPE 2 is a randomised Phase II/III trial studying radiotherapy dose escalation and positron emission tomography (PET) response in patients with oesophageal cancer treated with definitive chemoradiation. Patients with upper third oesophageal tumours >15cm ab oral with supraclavicular fossa (SCF) nodal involvement (N+ by TNM criteria) are eligible for participation, providing total contiguous disease length is <10cm. The current radiotherapy guidance does not specifically cover the scenario of involved SCF nodes. There are no widely available delineation protocols for this group of patients. Therefore, we developed a new protocol to provide guidance for clinicians and to ensure consistency of nodal outlining within the trial. Material and Methods A literature search was performed to review existing evidence for elective nodal irradiation (ELNI) and upper third oesophagus nodal anatomy. Existing nodal outlining atlases were reviewed, adapted and incorporated into existing SCOPE 2 radiotherapy guidance to produce the new protocol. Results There is no clinical evidence to recommend ELNI of the SCF in node negative patients, so this guidance only applies to patients with positive nodes in the SCF. The lymphatics of the proximal third oesophagus drain into bilateral deep cervical nodes that are contained within the SCF (2). Therefore, we have recommended that patients with positive SCF nodes receive irradiation of whole ipsilateral

Crania l

Latera l Crania l : latera l edge of SCM muscl e Cauda l : Juncti on 1 st rib / clavicl e

Caudal

Anterior Poster ior

Medial

Anteri or aspect of the scalen e muscl es

Cauda l to the cricoi d cartila ge

Exclud es thyroi d and trache a

Sternoclei do- mastoid (SCM) muscle

Cranial aspect of the sternoclavicular Joint

Table 1: Anatomical Boundaries of the Supraclavicular Fossa. Boundaries adapted from RTOG Breast Cancer Contouring Atlas and RTOG Head and Neck Atlases.

Image 1: A 5mm minimum margin is included around involved node. SCF volume is labelled CTVscf.

Image 2: Coronal view of bilateral SCF volume Summary of volumes:

GTVn = whole involved node, >30mm from GTVp CTVn = Involved node + 5mm in all directions CTVscf = CTVn + whole bilateral SCF PTVscf = CTVscf + 5mm margin in all directions (6mm sup- inf if using 3mm slices) PTV_5000 = PTVscf + standard dose PTV Conclusion This new delineation protocol provides a standardised approach that can be adopted by the wider radiotherapy community. Using this protocol within the context of a