Xerostomia-optimised IMRT Versus Standard IMRT in NPC

Xerostomia remains one of the most common radiation-induced toxicities, and approximately 80% to 90% of NPC patients still experience varying degrees of xerostomia post-IMRT. Among the major salivary glands, the parotid gland is the largest and produces 60% to 65% of the oral saliva output. Studies have revealed that xerostomia post-IMRT is mainly dependent on the irradiation dose of the parotid glands. Clinical target volumes (CTV) for the cervical nodal region starting from skull base have been the standard in nasopharyngeal carcinoma for several decades. Consequently, the parotid glands overlap with the target volumes and irradiation dose reaches 31.7 Gy to 43.9 Gy in most reports. Retrospective studies reveal that the lateral process of C1 is a suitable cranial edge for neck CTV delineation; therefore, the volume of the parotid glands exposed to high radiation doses can be greatly reduced. we conducted this trial comparing outcomes ,toxicities and QoL of xerostomia-optimized intensity-modulated radiotherapy versus standard intensity-modulated radiotherapy in nasopharyngeal carcinoma.