ESTRO meets Asia 2024 - Abstract Book

S193

Interdisciplinary – Head & neck

ESTRO meets Asia 2024

460

Proffered Paper

International consensus for the target volume delineation for NPC after ICT: First round results

Michael Benedict A Mejia 1 , Warren R Bacorro 1,2 , Nejla Fourati 3 , Hela Hammami Turki 4 , Ryan Anthony Agas 1 , Omar Nouri 3 , Audrey Larnaudie 5 , Melvin LK Chua 6 , Jamel Daoud 3 , Lester Bryan A Co 7 , Chong Zao 8 1 Radiation Oncology, University of Santo Tomas Hospital, Manila, Philippines. 2 Clinical Epidemiology, University of Santo Tomas Faculty of Medicine and Surgery, Manila, Philippines. 3 Radiation Oncology, University of Sfax, Sfax, Tunisia. 4 Radiation Oncology, Polyclinique International Amilcar, Tunis, Tunisia. 5 Radiation Oncology, Centre François Baclesse, Caen, Normandy, France. 6 Department of Head and Neck and Thoracic Cancers, Division of Radiation Oncology, National Cancer Centre Singapore, Singapore, Singapore. 7 Radiation Oncology, Riverside Bacolod Cancer Care Center, Bacolod, Philippines. 8 Department of Nasopharyngeal Carcinoma/Radiation Oncology, Sun Yat Sen University Cancer Center, Guangzou, China

Purpose/Objective:

Induction chemotherapy (ICT) is a therapeutic standard for locally advanced nasopharyngeal carcinomas (NPC) (1–3). However, published delineation consensus guidelines do not specify radiation therapy (RT) target volumes and dose levels based on response to ICT (4,5).

We sought to develop a consensus guideline towards harmonizing practices based on a systematic review and international expert opinion.

Material/Methods:

Between June and November 2023, after a scoping and systematic review, 4 clinical situations (CS), after ICT for NPC patients, were selected for the consensus questions: CS1) Optimal timing of chemoradiation; CS2) Optimal imaging modalities for simulation and target volume delineation; CS3) Optimal dose and fractionation; CS4) RT target volumes delineation (6). The consensus panel (CP) was composed of 12 radiations oncologists, 4 clinical oncologists, 3 radiologists, 1 nuclear medicine specialist, 2 medical physicists and 2 dosimetrists from different countries. From December 17-31, all CP were invited to answer the various questions related to the 4 clinical situations: 1 for CS1, 4 for CS2, 8 for CS3 and 11 for CS4. A modified e-Delphi method was employed. For each question, the possible responses were: strongly agree (SA), agree (A), disagree (D), and strongly disagree (SD). Consensus will have been reached if >50% voted to agree (SA+A) or disagree (SD+D). The vote will be uniform (U), if it constitutes 100%; strong (S) if ≥85; moderate (M) if 75-84%; or weak (W) if <75% (4).

Results:

First round of Delphi voting ended on January 10. There was a uniform consensus that (chemo)radiation should start 3-4 weeks after ICT. The simulation scan should be performed after ICT (U) and an additional simulation scan may be performed before ICT (W). MRI with contrast and with DWI were considered the optimal imaging modalities to be performed before (U and S respectively) and after (U and S respectively) ICT to help define RT target volume. No imaging is needed during ICT (M). Two dose levels (High and Intermediate risk) should be defined for the primary and nodal planning target volumes (PTV) (U and S respectively). Low-risk volume should not be defined for the primary (W) and may be defined for nodes (W). An integrated simultaneous boost of 33-35