ICHNO-ECHNO 2022 - Abstract Book

S67

ICHNO-ECHNO 2022

Poster: Multidisciplinary management

PO-0113 The impact of peer review with a radiologist in head and neck cancer radiotherapy planning

K. Chiu 1 , P. Hoskin 2 , A. Gupta 1 , R. Butt 2 , S. Terparia 2 , L. Codd 2 , Y. Tsang 2 , J. Bhudia 1 , H. Killen 1 , C. Kane 2 , S. Ghosh-Ray 3 , C. Lemon 1 , D. Megias 2 1 Mount Vernon Cancer Centre, Head and Neck Clinical Oncology, London, United Kingdom; 2 Mount Vernon Cancer Centre, Clinical Oncology, London, United Kingdom; 3 Paul Strickland Scanner Centre, Head and Neck Radiology, London, United Kingdom Purpose or Objective Quality assurance peer review is an important process in radiotherapy planning. Accurate radiographic interpretation of increasingly complex head and neck radiology is vital in radiotherapy volume delineation. Specialist radiologist input in peer review of head and neck radiotherapy planning has been introduced as a routine departmental approach. The aim was to evaluate this practice and to quantitatively analyse the changes made. Materials and Methods Head and neck patients treated with definitive and post-operative intensity modulated radiotherapy (IMRT) between August and November 2020 were reviewed. The incidence of major and minor changes, as defined by The Royal College of Radiologists guidelines, was prospectively recorded. A major change was defined as one that required alteration to prevent a geographical miss, or a change in the treatment paradigm. A minor change was one without which the original volume would still have been clinically acceptable. The amended IMRT volumes were retrospectively compared with the original volumes using Jaccard Index (JI) for conformity; Geographical Miss Index (GMI) to assess under-contouring; and Hausdorff Distance (HD) to measure the maximum distance between the volumes in three-dimension. Results In total 73 out of 87 (84%) patients were discussed. Changes were recommended in 38 (52%) patients; 28 out of 50 (56%) were from the definitive IMRT and 10 out of 23 (44%) from post-operative IMRT cases. Overall 30 (79%) patients had at least one major change, 8 (21%) had minor changes only. There were in total 99 amended IMRT volumes. Volumes with highest incidence of 'major' change were the primary gross tumour volume (GTVp) and therapeutic dose primary clinical target volume (CTVp_65), which was at 35% (17 out of 48) and 33% (20 out of 60) respectively. The incidence of 'major' change in the nodal GTV (GTVn) and therapeutic dose nodal CTV (CTVn_65) was 21% (9 out of 42) and 24% (12 out of 50) respectively. The overall median JI, GMI and HD of the amended volumes was 0.91 (interquartile range [IQR]=0.80–0.97), 0.06 (IQR=0.02– 0.18) and 0.42cm (IQR=0.20–1.17cm) respectively. Although less frequently altered, GTVn and CTVn_65 had the biggest magnitude of changes: The median JI, GMI and HD of GTVn was 0.89 (IQR=0.44–0.95), 0.11 (IQR=0.05–0.51), 3.71cm (IQR=0.31–6.93cm); CTVn_65 was 0.78 (IQR=0.59–0.90), 0.20 (IQR=0.07–0.31) and 3.28cm (IQR=1.22–6.18cm) respectively. This is in comparison to the median JI, GMI and HD of GTVp which was 0.94 (IQR=0.83–0.97), 0.04 (IQR=0.01–0.07), 0.36cm (IQR=0.22–0.45cm); CTVp_65 was 0.89 (IQR=0.81–0.96), 0.07 (IQR=0.02–0.14) and 0.42cm (IQR=0.24–0.68cm) respectively. There was no observed difference in the quantitative indices of the 85 ‘major’ and 14 ‘minor’ changed volumes (p=0.5). Conclusion Regular head and neck radiologist input in peer review is a valuable practice. The major and minor change classification may benefit from differentiation with quantitative indices but requires correlation with clinical outcomes. S. Ghosh Laskar 1 , S. Sinha 1 , P. Pai 2 , D. Nair 2 , J.P. Agarwal 1 , A. Budrukkar 1 , M. Swain 1 , D. Chaukar 2 , S.K. Thiagrajan 2 , K. Prabhash 3 , A.A. Moiyadi 4 , P. Shetty 4 1 Tata Memorial Hospital, Radiation Oncology, Parel Mumbai, India; 2 Tata Memorial Hospital, Head and Neck Surgical Oncology, Parel Mumbai, India; 3 Tata Memorial Hospital, Medical Oncology, Parel Mumbai, India; 4 Tata Memorial Hospital, Neurosurgery, Parel Mumbai, India Purpose or Objective Primary tumours of the external auditory canal (EAC) and Temporal Bone (TB) are rare entities with very few large reports of outcomes and toxicities. The primary endpoint of the study was event-free survival (EFS). Materials and Methods A retrospective audit of all consecutive EAC and TB tumours treated at our institute between January 2007 and December 2019 was undertaken after Institutional Review Board approval. . Data was extracted from the institutional skull base registry and electronic medical records of the patients. Locally advanced salivary gland tumours involving the temporal bone and histology like sarcoma, chondrosarcoma and aneurysmal bone cyst and metastases were excluded from the study. The s taging was done as per the Pittsburg staging system. Primary surgery (either open or endoscopic) with margin negative resection whenever feasible was performed. The surgical procedures included wide excision or Lateral Temporal Bone Resection (LTBR), Subtotal Temporal Bone Resection (STBR), or Total Temporal Bone Resection (TTBR). After discussion in a multidisciplinary clinic, the decision regarding final treatment, surgery or induction chemotherapy followed by surgery and appropriate adjuvant therapy or definitive (chemo) radiotherapy was taken. PO-0114 Patterns of care and outcomes in External Auditory Canal and Temporal Bone Tumors