Objective: Cervical lymph node metastasis is an important prognostic factor in squamous cell carcinoma of the head and neck, decreasing survival by up to < 50%. Parotid gland squamous cell carcinoma most commonly spreads to nodes in the parortid and cervical levels I, II, and III.
Study Design: Retrospective analysis of a population-based tumor registry.
Setting: Academic medical center.
Subjects and Methods: The Surveillance, Epidemiology, and End Results (SEER) database was queried for cases of squamous cell carcinoma of the parotid gland from 2004 to 2013 (1,912 cases). Resulting data including patient demographics, clinicopathological features, topographical distribution of nodal metastasis, and survival based on lymph node level involvement were analyzed. Of the 1912 cases, 1548 had regional metastasis based on SEER lymph node staging that had been determined by either surgical neck dissection, radiographic imaging, or autopsy. For 5-year disease-specific survival (DSS) analysis, only surgical lymph dissection data was used in the Kaplan Meier test because surgical labeling is more accurate and important for survival (636 cases).
Results: Of the 1912 cases identified with squamous cell carcinoma of the parotid gland, most patients were male (81.6%) with a male-to-female ratio of 4.4:1.0. Most of the patients diagnosed were white (93.1%) and the age cohort with the highest proportion of cases was age 80+ years (39%). In total, 636 patients were identified with SCCa who underwent neck dissection. Level I (n=322), followed by levels II and III (n=211), represented the most commonly involved nodal basins. Higher T-stages did not seem to correlate with increased nodal metastasis at any level. The 5-year disease-specific survival (DSS) for patients with only level I metastasis was 74.8% compared with 60.9% for level II and III (P = 0.616), 68.2% for level IV (P =0.498), and 50.3% for the level V group (P = 0.002). When nodal metastasis involved the lateral neck (level II, III, IV, and V), it appears that the addition of adjuvant radiation to surgery improves 5-year disease- specific survival. However, this was only statistically significant for level II and III involvement (68.2% vs 37.1%, P = 0.001).
Conclusion: Parotid squamous cell carcinoma commonly involves intraparotid lymph nodes as well as level I. Involvement of nodal level V portends a worse prognosis. Multimodality therapy should be considered for patients with lateral neck lymph node involvement.