Prognostic Effect of Neck Dissection and Risk Factors for Occult Lymph Node Metastasis in cN0 Parotid Carcinoma

Objective

This study aimed to explore the prognostic effect of neck dissection and to identify risk factors associated with occult lymph node metastasis (OLNM) in clinically node-negative (cN0) parotid carcinoma (PC).

Methods

A retrospective analysis was conducted on cN0 PC patients who underwent primary surgery at the National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences, between 2012 and 2022. Kaplan–Meier (KM) survival analyses were carried out to evaluate differences in progression-free survival (PFS) and overall survival (OS) between patients undergoing neck dissection and those who did not. Clinical variables associated with OLNM in the neck dissection group were assessed using univariate and multivariate logistic regression analyses.

Results

Among 472 PC patients, 133 were classified as cN0 following initial surgery, of whom 75 (56.4%) underwent neck dissection. Pathological lymph node metastases were confirmed in 20 (26.7%) patients in the neck dissection cohort. Poor tumor differentiation was identified as an independent risk factor for OLNM (p = 0.017). No significant differences in PFS or OS were observed between the no-neck dissection and neck dissection groups for patients with low-grade or well-differentiated tumors (p > 0.05). However, neck dissection was associated with significantly prolonged PFS in patients with tumors of higher grade or low to moderate differentiation (p < 0.05). Notably, OS did not improve with neck dissection across all subgroups (p > 0.05).

Conclusion

Poorly differentiated tumors in cN0 PC are independently associated with a higher risk of OLNM. While prophylactic neck dissection may enhance PFS in patients with higher grade or poorly differentiated tumors, it does not confer a survival benefit in terms of OS. These findings support the selective use of neck dissection in patients with higher risk tumor profiles.