Table 1.

Summary of current radiotherapy considerations for nasopharyngeal carcinoma (NPC).

Components of Radiotherapy Planning for NPC	Areas of Consideration and Recent Developments
Target delineation (gross tumor volume (GTV))	-Reference to pre-treatment findings of high-resolution fiberoptic endoscopy, magnetic resonance imaging (MRI), and positron emission topography (PET) images -Input from diagnostic radiologists specializing in head and neck cancers
Target delineation (clinical target volume (CTV): primary tumor)	-CTV margin reduction -Sparing contralateral structures in unilateral diseases (i.e., gross tumor that does not cross mid-sagittal plane) -Reduction in CTV upon response to induction chemotherapy
Target delineation (CTV: regional lymphatics)	-Refinement of the delineation boundaries of nodal levels according to knowledge of nodal topographic characteristics -Omission of lower neck irradiation in uninvolved necks
Dose de-escalation	-Dose reduction from 70 Gray (Gy) to 60 Gy upon response to induction chemotherapy -The “gradient-dose” concept of delivering a dose gradient proportional to tumor volume and/or metabolic activity
Dose escalation	-Functional image-guided dose painting to sub-volumes of the target with a high tumor load or a radio-resistant region
Sparing of organ at risk (OAR)	-Cochlea-sparing intensity-modulated radiotherapy (IMRT) -Hotspot control of the hypoglossal nerve
Others	-Proactive adaptive radiotherapy -Clinical and radiation dosimetric benefits of particle therapies -Incorporation of artificial intelligence in auto-segmentation and plan optimization