Patterns of lymph node metastasis and treatment outcomes of parotid gland malignancies.

Abstract

Background: This study aimed to characterize the pattern of cervical lymph node spread and evaluate prognostic factors and outcomes of surgery and postoperative adjuvant therapy in primary parotid carcinoma (PPC).

Methods: We retrospectively enrolled 136 patients with PPC. The primary outcomes were disease-free survival (DFS) and overall survival (OS). We used Cox hazards models to assess variables influencing survival, and chi-square tests and logistic regression models to evaluate correlations between pN + and clinicopathological factors.

Results: Pathology-confirmed lymph node metastasis was detected in 60.0% and 84.1% of the patients with cT1-2 and cT3-4 tumors, respectively. The occult metastasis rate in cN0 was 55.2%. Level II metastasis was most common (93.2%), followed by level I (49.3%). Histological type, histologic grade, pT stage, and AJCC stage were significant risk factors for lymph node metastasis. One- and five-year OS were 86.0% and 49.3%, respectively (median, 60 months) and 71.6% and 34.8%, respectively, for DFS (median, 24 months). Surgery with ¹²⁵I seed implant brachytherapy conferred survival benefits to patients. Predictive factors for DFS were pT stage, pN stage, histological type, histological grade, and management strategy, and for OS, pT stage, pN stage, histological type, and histological grade.

Conclusion: Histological high grade and advanced T classification were associated with occult lymph node metastasis. Postoperative radiotherapy (RT)/radiochemotherapy (RCT), conferred significant survival benefits in PPC. Neck dissection in patients with cN0 cancer significantly improved DFS and should be performed on those with high-grade and/or advanced T-stage tumors.