A protocol for international consensus guideline development on the delineation of radiotherapy target volumes for nasopharyngeal carcinoma after induction chemotherapy

Background: Induction chemotherapy (ICT) is a therapeutic standard for locally advanced nasopharyngeal carcinoma (NPC). Radiotherapy (RT) target volume delineation protocols and dose level prescriptions vary importantly in published studies. We aim to develop a consensus guideline to harmonize practices in this regard. Methods: The study consists of the following phases: Consensus Scope Definition by focus group discussion (FGD); Evidence Gap Identification by a scoping review of guidelines and literature reviews; Evidence Review and Synthesis by a systematic review of experimental and observational studies and Drafting of Consensus Statements by FGD; and Consensus Voting by modified Delphi process and FGD. The Task Force consists of radiation oncologists from intermediate- and high-endemicity regions with expertise in the treatment of NPC, evidence review and/or consensus guideline development. The Consensus Panel (CP) will consist of relevant specialists from intermediate- and high-endemicity regions or with expertise in the treatment of NPC. The consensus voting process will entail a presentation and discussion of evidence summaries, followed by 1–3 rounds of voting. Each round will consist of an independent voting using the modified e-Delphi process followed by an en banc review and deliberation of the summary of the votes. Up to three rounds will be conducted, after which items for which no consensus was achieved will be indicated thus. The consensus guideline will be reported per the ACCORD guidance document and reviewed externally using the AGREE II checklist. Discussion: An international consensus guideline on the delineation of RT target volumes and corresponding dose levels in post-induction NPC, and timing and modalities for imaging will help harmonize practices and improve the comparison of reported outcomes. Trial Registration: PHRR230911-006104 (https://www.herdin.ph/index.php/aggregate-report?view=research&layout=details&cid=6104).