PURPOSE: The treatment of nasopharyngeal carcinoma (NPC) requires high radiation doses. The balance of the risks of local recurrence due to inadequate tumor coverage versus the potential damage to the adjacent organs at risk (OARs) is of critical importance. With advancements in technology, high target conformality is possible. Nonetheless, to achieve the best possible dose distribution, optimal setting of dose targets and dose prioritization for tumor volumes and various OARs is fundamental. Radiation doses should always be guided by the ALARP (As Low As Reasonably Practicable) principle. There are marked variations in practice. This study aimed to develop a guideline to serve as a global practical reference.METHODS: A literature search on dose tolerances and normal tissue complications following treatment for NPC was conducted. In addition, published guidelines and protocols on dose prioritization and constraints were reviewed. A text document and preliminary set of variants was circulated to a panel of international experts with publications and/or extensive experience in the field. An anonymized voting process was conducted to rank the proposed variants. A summary of the initial voting and different opinions expressed by members were then re-circulated to the whole panel for review and re-consideration. Based on the comments of the panel, a refined second proposal was re-circulated to the same panel. The current guideline was based on majority voting following repeated iteration for final agreement.RESULTS: Variation in opinion among international experts was repeatedly iterated to develop a guideline describing appropriate dose prioritization and constraints. The percentage of final agreement on the recommended parameters and alternative views is shown. The rationale for the recommendations and the limitations of current evidence are discussed.CONCLUSIONS: Through this comprehensive review of available evidence and interactive exchange of vast experience by international experts, a guideline was developed to provide a practical reference for setting dose prioritization and acceptance criteria for tumor volumes and OARs. The final decision on the treatment prescription should be based on the individual clinical situation and patient's acceptance of optimal balance of risk.
View details for DOI 10.1016/j.ijrobp.2019.06.2540
View details for PubMedID 31276776