Objective: Extracapsular extension (ECE) in nodal metastases is widely believed to be a poor prognostic factor in head and neck squamous cell cancers (SCC), but supporting evidence has been limited in the existing literature. We have conducted an analysis of the largest series of extracapsular extension in node-positive head and neck cancer cases to date.
Methods: Using the SEER database, we characterized 15,029 cases of N1 or greater head and neck cancers with documented ECE status, evaluating incidence for several major head and neck regions, and investigating correlations between ECE and patient demographics, primary tumor site, and extent of local, regional and distant disease.
Results: 10-year disease-specific survival (DSS) and overall survival (OS) were evaluated, with a significant decline in survival seen for pathologically diagnosed ECE (p<0.001) and further still for clinically diagnosed ECE (P<0.001). This trend was strongly present in all head and neck cancer regions investigated. However, the survival impact of pathologically diagnosed ECE was seen to be heavily dependent on factors such as primary site, race, and gender (P<0.001 – 0.017). ECE was seen to have the greatest negative effect on survival for salivary gland and nasopharyngeal SCC (all p<0.001). There was a slight but statistically significant propensity for advanced age in patients with ECE (60.3 vs. 59.8, p=0.030). The mean number of positive nodes was significantly higher in patients diagnosed with ECE (4.51 vs. 2.23, p<0.001). ECE was no more common among any racial or gender category, but did display a higher prevalence in lip (31.1%), salivary gland (29.9%), oral cavity (29.7%), and hypopharyngeal primary cancers (28.3%; all p<0.001). The rate of ECE doubled between T0 and T4 lesions (16.2 vs. 31.5%, p<0.001), and between N1 and N3 neck disease (17.4 vs 39.0%, p<0.001). ECE was closely associated with increasing maximal node diameter (p<0.001) and with involvement of lower or multiple neck levels (all p<0.001).
Conclusion: To our knowledge, this study is the largest series investigating ECE in head and neck SCC. Variations in the survival impact of ECE appear to depend on the degree of spread evident at diagnosis, as well as demographic factors. The prevalence of ECE was seen to vary with the location and size of the primary tumor, as well as the location and general extent of nodal involvement.