ESTRO 2023 - Abstract Book

S123

Saturday 13 May

ESTRO 2023

Conclusion This study showed a concentration of the results on specific countries, with lack of data on key factors associated with clinical decision making, such as comorbidity, demonstrating the importance of standardised population-based data collection to support evidence, decision-making and practice.

PD-0162 Thymic epithelial tumour radiotherapy: A survey of current UK clinical practice S. Robinson 1 , A. Gault 2 , D. Gilligan 3

1 The Royal Marsden NHS Foundation Trust, Radiotherapy Department, London, United Kingdom; 2 Newcastle University, Translational and Clinical Research Institute, Newcastle, United Kingdom; 3 Cambridge University Hospitals NHS Foundation Trust, Department of Oncology, Cambridge, United Kingdom Purpose or Objective Thymic epithelial tumours (TETs) are rare tumours without large clinical trials to guide management. In particular, the role of radiotherapy (RT) is often guided by expert consensus and clinician experience. Given the presumed variation in practice we sought to understand the current use of RT in clinical practice in the UK. Materials and Methods An online survey was developed under the auspices of the UK National Oncology Trainee Collaborative for Healthcare research (NOTCH) with supervision from a Thoracic Clinical (Radiation) Oncology Consultant with expertise in TET RT. The survey was emailed to a named consultant at each UK RT centre and publicised via national groups. Follow-up emails were sent to encourage participation during the survey window (March 2022-July 2022). Results 47/60 (78%) UK RT centres responded, with 36 (77%) complete responses. Centres have a median of 3 Clinical (Radiation) Oncology Consultants who treat TETs (range 0-12) and treat a median of 2-3 TETs per year (range: 0-1 [13%, 6/47] to 20+ [6%, 3/47]). Very few centres have a TET lead (19%, 9/47), a TET specialist nurse (6%, 3/47) or a TET specialist neurologist (23%, 11/47). Cases are generally discussed at local lung MDTs (64%, 30/47), but 85% (40/47) of respondents agreed TETs should be discussed at TET-specific MDTs due to their rarity. Most centres follow international guidelines when deciding to offer RT (91%, 43/47), of which the majority follow the 2015 ESMO guidelines (83%, 38/47). However, 23% would consider post-operative RT for some completely resected stage I Thymomas (9/39), and 23% would not offer post-operative RT for all stage III/IVa Thymomas (9/39). Additionally, as can be seen in Table 1, there is substantial variation in which patients with stage II Thymoma would be offered post-operative RT at different centre, with increasing stage and aggressive histology leading to increased concordance. Regarding RT planning, 67% (24/36) use 4D-CT simulation, 86% (31/36) use VMAT, and 69% (25/36) use daily cone beam CT. A minority (17%, 6/36) include elective areas within their target volume, and 53% (19/36) vary their target volume based on resection status (19/19), histology (14/19) or stage (14/19). Peer review occurs with another Clinical (Radiation) Oncologist in 75% (27/36), with some centres utilising thoracic radiologists (11%) or thoracic surgeons (22%). Follow up is primarily with Clinical (Radiation) Oncologists (89%, 32/36) and patients are generally seen six monthly (56%, 20/36) for five years (50%) or >7-10 years (31%). CT imaging is the most common imaging modality and occurs six monthly (36%) or annually (47%).

Conclusion Despite international guidelines there is still significant variation in treatment and follow up of TETs across the UK, as highlighted by this comprehensive survey of current clinical practice. As demonstrated, the development of wider TET