Risk of Cervical Metastasis in Primary Parotid Gland Malignancies: A Yo-IFOS Multicenter Retrospective Longitudinal Study

Background: Cervical lymph node metastasis is a major adverse prognostic factor in primary parotid gland malignancies. However, the incidence, level-specific distribution, and independent predictors of nodal metastasis remain incompletely defined in large contemporary multicenter cohorts. Methods: A retrospective longitudinal multicenter study was conducted across 17 tertiary referral centers. Adult patients with histopathologically confirmed primary parotid gland carcinoma who underwent parotidectomy with concurrent neck dissection were included. The primary outcome was pathologically confirmed cervical lymph node metastasis. Secondary outcomes included level-specific nodal distribution, identification of independent risk factors, overall survival (OS), and disease-specific survival (DSS). Results: A total of 380 patients were included. Pathological cervical lymph node metastasis was identified in 94 patients (24.7%). Metastases most frequently involved Level II (IIa 17.1%; IIb 11.1%). Salivary duct carcinoma demonstrated the highest rate of nodal metastasis (58.7%). On multivariate analysis, high histological grade and lymphovascular invasion (LVI) were independent predictors of nodal metastasis (p < 0.05). Five-year OS for the entire cohort was 64.4%. Patients with nodal metastasis had significantly worse survival compared with node-negative patients (p < 0.001). Conclusions: Cervical lymph node metastasis occurs in approximately one-quarter of surgically staged primary parotid gland malignancies and predominantly involves Levels II-III. High-grade histology and LVI independently predict nodal involvement. These findings support a risk-adapted approach to elective neck management based on histological and pathological risk stratification.