This retrospective observational study aims to evaluate the association between neck tumor burden and high-risk imaging features with locoregional recurrence and distant metastasis in patients with stage N3 nasopharyngeal carcinoma, and to explore the potential benefits of neck dissection, with or without re-irradiation or systemic therapy, in improving regional control and survival.

The key questions addressed are whether high N burden and high-risk imaging features are significantly correlated with neck recurrence and distant metastasis, and whether salvage neck treatment (such as neck dissection ± re-irradiation/systemic therapy) can improve regional control and survival outcomes in this high-risk population.

Nasopharyngeal carcinoma (NPC), due to its anatomical proximity to the skull base and critical cervical structures, is primarily treated with radiotherapy. However, even with current standard treatments, a subset of patients still develop locoregional failure with poor outcomes. Previous data have shown that the 5-year locoregional control rate for stage IV disease is approximately 80.7%, corresponding to a failure rate of about 20%. Among these, patients with T1-4N3 disease have a lower 3-year distant failure-free survival compared with T4N0-2, indicating that high N stage is associated not only with regional recurrence but also with increased risk of distant metastasis. Based on this, we hypothesize that high nodal burden and high-risk imaging features are significantly associated with cervical recurrence and distant metastasis, and that appropriate and timely salvage treatment to the neck (such as neck dissection with or without re-irradiation/systemic therapy) may improve regional control and survival.

Inclusion Criteria:

• Age ≥ 18 years.
• Pathologically confirmed diagnosis of nasopharyngeal carcinoma (NPC).
• Stage IV disease (Tany N3) according to the 8th edition of the AJCC staging system.
• Completion of definitive concurrent chemoradiotherapy (CCRT), or induction chemotherapy (IC) followed by radiotherapy/CCRT.
• Availability of complete clinical imaging and medical records before and after treatment for efficacy and prognostic analysis.

Exclusion Criteria:

• Presence of distant metastasis at initial diagnosis.
• Prior history of treatment for other head and neck malignancies, aside from definitive therapy for NPC (to avoid confounding prognosis).
• Incomplete or prematurely discontinued definitive radiotherapy, resulting in failure to complete the planned curative treatment.
• Lack of complete pathology report, clinical imaging, or treatment records, making effective analysis impossible.

The study population includes adult patients aged 18 years or older with pathologically confirmed nasopharyngeal carcinoma (NPC), staged as Stage IV (Tany N3) according to the 8th edition of the AJCC staging system. All participants have completed definitive concurrent chemoradiotherapy (CCRT) or induction chemotherapy (IC) followed by radiotherapy/CCRT, and have complete clinical imaging and medical records before and after treatment for subsequent efficacy and prognostic analysis. This cohort represents high-risk patients with advanced nodal disease, characterized by increased risks of both locoregional recurrence and distant metastasis, making them suitable for evaluating current treatment outcomes and subsequent management strategies.