Lymph node ratio as a prognostic factor for survival in patients with head and neck squamous cell carcinoma

Abstract

Objective

The purpose of this study is to validate the concept of lymph node ratio (LNR) in head and neck squamous cell carcinoma (HNSCC).

Methods

A total of 63 patients with HNSCC who underwent resection of the primary tumor combined with neck dissection in our institution were analyzed in this study. LNR was defined as the number of positive lymph nodes divided by the total number of lymph nodes excised. LNR was categorized into two groups (<0.068 and ≥0.068) according to the results of receiver-operating characteristic plots for determination of the cut-off value.

Results

LNR ≥ 0.068 was associated with poor overall survival (OS), progression-free survival (PFS) and locoregional recurrence-free survival (LRFS) after resection of the primary tumor combined with neck dissection in patients with HNSCC. Univariate and multivariate data analysis showed that LNR ≥ 0.068 was an independent prognostic factor for OS, PFS and LRFS. Both pathological T stage status (pT3 or 4) and ≥3 positive LNs were also an independent prognostic factors for PFS in patients with HNSCC in our univariate and multivariate analysis.

Conclusion

These results suggested that LNR could be useful tools in identifying HNSCC patients with poor outcomes.

Introduction

Head and neck squamous cell carcinoma (HNSCC) consistently ranks as one of the ten most frequently diagnosed cancers in the world [1]. Despite advances in the treatment of HNSCC, the survival of patients with HNSCC has not significantly improved over the past several decades. This is primarily because of our inability to control the regional and distant spread of this disease [2]. In particular, HNSCC patients frequently suffer from treatment failure in the form of local and regional recurrences. Indeed, the presence of cervical lymph node metastasis is the most important prognostic indicator for the prediction of HNSCC patient survival to date [3].

Historically, clinical tumor-node-metastasis (TNM) stage has often been used as criteria for the management of treatment for patients with HNSCC. For cervical lymph node metastasis in HNSCC, N staging is based on the size, number, laterality, and fixation of positive nodes. However, node stage is not always a useful prognostic predictor in HNSCC [4]. We, therefore, need to consider pathological features including lymph node metastatic status to manage postoperative adjuvant therapy after surgical treatment for patients with HNSCC. As the presence of extranodal extension (ENE) of cervical lymph node metastasis in HNSCC has been reported to be associated with higher rates of regional and distant failure [5], the development of pathologically involved lymph nodes with ENE after neck dissection is thought to be one of most important adverse pathologic features. The national comprehensive cancer network (NCCN) guidelines recommend clinicians to consider postoperative adjuvant radiotherapy (RT) or chemoradiotherapy (CRT) in the case of adverse pathologic features including ENE and/or a positive margin [6]. However, to better manage postoperative adjuvant therapy in patients with HNSCC, additional pathological features for the prediction of survival in HNSCC patients are still required.

Lymph node ratio (LNR) has previously been reported to reliably predict survival in some solid malignancies such as breast cancer, colon cancer and gastric cancer [7], [8], [9]. Indeed, the importance of LNR as a prognostic factor in HNSCC has been also reported recently [10], [11], [12], [13], [14], [15]. To determine the applicability of LNR in predicting survival in patients with HNSCC, the study in comparison with adverse pathological factors such as the number of positive cervical lymph nodes (LNs) or the presence of ENE would be still required.

In this study, we retrospectively reviewed the institutional records of patients with HNSCC who underwent resection of the primary tumor combined with neck dissection in our institution in order to assess the prognostic significance of LNR on survival in comparison with adverse pathological factors.