International guideline for the delineation of the clinical target volumes (CTV) for nasopharyngeal carcinoma

Publication date: Available online 15 November 2017
Source:Radiotherapy and Oncology
Author(s): Anne W. Lee, Wai Tong Ng, Jian Ji Pan, Sharon S. Poh, Yong Chan Ahn, Hussain AlHussain, June Corry, Cai Grau, Vincent Grégoire, Kevin J. Harrington, Chao Su Hu, Dora L. Kwong, Johannes A. Langendijk, Quynh Thu Le, Nancy Y. Lee, Jin Ching Lin, Tai Xiang Lu, William M. Mendenhall, Brian O'Sullivan, Enis Ozyar, Lester J. Peters, David I. Rosenthal, Yoke Lim Soong, Yungan Tao, Sue S. Yom, Joseph T. Wee
PurposeTarget delineation in nasopharyngeal carcinoma (NPC) often proves challenging because of the notoriously narrow therapeutic margin. High doses are needed to achieve optimal levels of tumour control, and dosimetric inadequacy remains one of the most important independent factors affecting treatment outcome.MethodA review of the available literature addressing the natural behaviour of NPC and correlation between clinical and pathological aspects of the disease was conducted. Existing international guidelines as well as published protocols specified by clinical trials on contouring of clinical target volumes (CTV) were compared. This information was then summarized into a preliminary draft guideline which was then circulated to international experts in the field for exchange of opinions and subsequent voting on areas with the greatest controversies.ResultsCommon areas of uncertainty and variation in practices among experts experienced in radiation therapy for NPC were elucidated. Iterative revisions were made based on extensive discussion and final voting on controversial areas by the expert panel, to formulate the recommendations on contouring of CTV based on optimal geometric expansion and anatomical editing for those structures with substantial risk of microscopic infiltration.ConclusionThrough this comprehensive review of available evidence and best practices at major institutions, as well as interactive exchange of vast experience by international experts, this set of consensus guidelines has been developed to provide a practical reference for appropriate contouring to ensure optimal target coverage. However, the final decision on the treatment volumes should be based on full consideration of individual patients' factors and facilities of an individual centre (including the quality of imaging methods and the precision of treatment delivery).



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