Primary target volume delineation 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, Head and Neck Cancer International Group, the European Society for Radiotherapy and Oncology, and the American Society for Radiation Oncology jointly developed evidence-based guidelines and a contouring atlas for primary target volume delineation for radiotherapy in nasopharyngeal carcinoma. The guidelines systematically address three crucial challenges: margin design of clinical target volumes; target volume delineation after induction chemotherapy; and low-risk clinical target volume delineation based on local stepwise extension patterns. Based on a comprehensive systematic review and critical appraisal by an international multidisciplinary panel of 50 nasopharyngeal carcinoma specialists from 17 countries and regions, these guidelines are in keeping with advances in nasopharyngeal carcinoma diagnosis and treatment, embodying contemporary treatment concepts, and elaborating on the differences in practice. These guidelines aim to support global clinical practice in radiotherapy target volume delineation, substantially enhancing homogeneity and reducing variability in nasopharyngeal carcinoma target delineation.