Target volume delineation of the neck for radiotherapy in nasopharyngeal carcinoma: CSTRO, CACA, CSCO, HNCIG, ESTRO, and ASTRO guidelines and contouring atlas.

The Chinese Society for Therapeutic Radiology Oncology, the Chinese Anti-Cancer Association, the Chinese Society of Clinical Oncology, the Head and Neck Cancer International Group, the European Society for Radiotherapy and Oncology, and the American Society for Radiation Oncology collaboratively developed evidence-based guidelines and a comprehensive contouring atlas for neck target volume delineation in nasopharyngeal carcinoma. These guidelines address five key challenges in modern radiotherapy practice: margin design of clinical target volume; nodal target volume delineation after induction chemotherapy; delineation of equivocal nodes evident on imaging; low-risk clinical target volume delineation based on regional stepwise extension patterns; and modifications for anatomical boundaries of lymphatic areas. Developed through a rigorous systematic review and expert appraisal process by a panel of 50 international, multidisciplinary members from 17 countries and regions, these guidelines incorporate the latest advances in nasopharyngeal carcinoma diagnosis and treatment. They reflect contemporary therapeutic concepts and elaborate on current practice variations. These guidelines aim to standardise global practice, substantially improving consistency and reducing variability in nasopharyngeal carcinoma radiotherapy target delineation.