The feasibility of reduced-dose radiotherapy in childhood nasopharyngeal carcinoma with favorable response to neoadjuvant chemotherapy

Delineation of reduced CTV2 on the basis of the characteristics and distribution of cervical lymph node metastasis in nasopharyngeal carcinoma

INTRODUCTION

The core objective of this study was to precisely locate metastatic lymph nodes, identify potential areas in nasopharyngeal carcinoma patients that may not require radiotherapy, and propose a hypothesis for reduced target volume radiotherapy on the basis of these findings. Ultimately, we reassessed the differences in dosimetry of organs at risk (OARs) between reduced target volume (reduced CTV2) radiotherapy and standard radiotherapy.

METHODS AND MATERIALS

A total of 209 patients participated in the study. We used image registration techniques to map patients' neck metastatic lymph nodes onto a template CT of healthy individuals. Using MIM software, we integrated all patients' lymph node images onto the template CT images and conducted an in-depth analysis of their distribution characteristics and metastatic patterns. Subsequently, we randomly selected the localization images of 30 patients and used paired t test methods to compare the differences in the dosimetry of target volumes and OARs between reduced target volume radiotherapy and standard radiotherapy.

RESULTS

A total of 2314 metastatic lymph nodes were identified and mapped. There were no metastatic lymph nodes observed at level VIIb or within the lateral border of the common carotid artery. The percentages of metastatic lymph nodes at levels Ia, Ib, IIa, IIb, III, IVa, IVb, Va, Vb, Vc, VIa, VIb, VIIa, VIIb and VIII accounted for 0%, 1.5%, 22.8%, 41.1%, 15.9%, 3.0%, 0%, 4.4%, 1.0%, 0.3%, 0%, 0%, 9.7%, 0% and 0.3%, respectively, of the 2314 metastatic lymph nodes. Further analysis of the dosimetric outcomes revealed a significantly lower mean dose to the oral cavity, laryngeal cavity, esophagus, trachea, pharyngeal constrictor muscles, parotid gland, submandibular gland and thyroid gland with the implementation of reduced-target radiotherapy than with standard radiotherapy.

CONCLUSION

IMRT sparing level I, IVb, VI, and VIIb lymph nodes and the area within the lateral border of the common carotid artery for stage II-IVa NPC patients is feasible. This method can significantly reduce the dose to peripheral organs at risk.

Optimizing Hearing Outcomes in Nasopharyngeal Cancer Survivors in the Era of Modern Radiotherapy and Systemic Therapy

Intensity-modulated radiation therapy (IMRT) improves disease control and reduces treatment-related toxicity in patients with localized nasopharyngeal carcinoma (NPC). However, due to the proximity of the auditory apparatus to the treatment volume and the frequent incorporation of cisplatin-based chemotherapy, treatment-related sensorineural hearing loss (SNHL) remains a common debilitating complication among NPC survivors. The reported crude incidence of SNHL following IMRT for NPC varies widely at 1-46% due to differences in auditory assessment methods and thresholds, follow-up durations, chemotherapy usage, and patient compositions. International guidelines and radiation dosimetric studies have recommended constraining the cochlear mean dose to less than 44-50 Gy, but the risk of SNHL remains high despite adherence to these constraints. Potential strategies to improve hearing outcomes in NPC survivors include cautious de-escalation of radiotherapy dose and volume, individualization of cochlear constraints, optimization of radiotherapy planning techniques, and the use of substitutes or alternative schedules for cisplatin-based chemotherapy. The addition of immune checkpoint inhibitors to chemoradiotherapy did not impact ototoxicity. Prospective studies that employ both objective and patient-reported auditory outcomes are warranted to test the long-term benefits of various approaches. This article aims to provide a comprehensive review of the incidence and radiation dose-toxicity relationship of SNHL in NPC survivors and to summarize potential strategies to optimize hearing outcomes in relation to nuances in radiotherapy planning and the selection of systemic therapy.

Current Radiotherapy Considerations for Nasopharyngeal Carcinoma

Radiotherapy is the primary treatment modality for nasopharyngeal carcinoma (NPC). Successful curative treatment requires optimal radiotherapy planning and precise beam delivery that maximizes locoregional control while minimizing treatment-related side effects. In this article, we highlight considerations in target delineation, radiation dose, and the adoption of technological advances with the aim of optimizing the benefits of radiotherapy in NPC patients.