Metastatic lymph node burden predictive of survival in patients undergoing primary surgery for laryngeal and hypopharyngeal cancer.

Purpose: Metastatic lymph node (LN) burden is one of the most important prognosticators in human solid cancers, but has rarely been examined in laryngeal and hypopharyngeal cancers (LHC). We evaluated the nodal factors predictive of recurrence and survival in patients with LHC.

Methods: This study included 141 consecutive patients who underwent primary surgery and neck dissection for previously untreated LHC at our tertiary referral centre. Nodal factors included the presence of pathological LN metastasis, number of positive LNs, LN ratio, and extra-nodal extension (ENE). Our proposed N classification was analysed by recursive partitioning analysis and compared with the AJCC and other N classifications using the c-index. Univariate and multivariate Cox proportional hazard regression analyses were used to define significant predictors of post-treatment disease-free survival (DFS) and overall survival (OS).

Results: Of the 141 patients, 66 (46.8%) had positive LNs, and 27 (19.1%) had ENE. In multivariate analyses, the number of positive LNs was strongly associated with DFS and OS outcomes (P < 0.01). Our new N classification was proposed with four categories, such as N0 (0 LN +), N1 (1 LN +), N2 (2-4 LN + or ENE) and N3 (≥ 5 LN +). The C-index of our new N classification improved the OS prediction (0.718) compared with the AJCC and the other N classifications (0.704-0.713).

Conclusion: Metastatic LN burden is an important predictor of survival in patients with LHC. A proposed N classification using the number of positive LNs and ENE might improve the LHC survival prediction.