Lymph node ratio for postoperative staging of laryngeal squamous cell carcinoma with lymph node metastasis

Abstract

Background: Lymph node metastasis has a significant impact on laryngeal cancer prognosis. The role of lymph node ratio (LNR, ratio of metastatic to examined nodes) in the staging of laryngeal cancer was not reported.

Patients and methods: Records of laryngeal cancer patients with lymph node involvement from Surveillance, Epidemiology, and End Results database (SEER, training set, N = 1963) and Fudan University Shanghai Cancer Center (FDSCC, validating set, N = 27) were analyzed for the prognostic value of LNR. Kaplan-Meier survival estimates, the Log-rank χ² test and Cox proportional hazards model were used for univariate and multivariate analysis. Optimal LNR cutoff points were identified by X-tile.

Results: Optimal LNR cutoff points classified patients into three risk groups R1 (≤0.09), R2 (0.09-0.20) and R3 (>0.20), corresponding to 5-year cause-specific survival and overall survival in SEER patients of 55.1%, 40.2%, 28.8% and 43.1%, 31.5%, 21.8%, 2-year disease free survival and disease specific survival in FDSCC patients of 74.1%, 62.5%, 50.0%, and 67.7%, 43.2%, 25.0%, respectively. R3 stratified more high risk patients than N3 with the same survival rate, and R classification clearly separated N2 patients to 3 risk groups and N1 patients to 2 risk groups (R1-2 and R3).

Conclusions: R classification is a significant prognostic factor of laryngeal cancer and should be used as a complementary staging system of N classification.

Figure 1. Kaplan–Meier survival estimates according to pN classification and R classification of SEER laryngeal cancer patients with lymph node metastasis: cause-specific survival (A) and overall survival (B) of the SEER set with different pN classification; cause-specific survival (C) and overall survival (D) of the SEER set with different R classification.

Figure 2. Kaplan–Meier survival estimates of different R classification patients of individual N classification.

The cause-specific survival (A) and overall survival (B) of individual R classification for pN1 patients; cause-specific survival (C) and overall survival (D) of individual R classification for pN2 patients.