Prognostic value of lymph node involvement in oral squamous cell carcinoma

Abstract

Objectives: Different parameters have been identified in patients with oral squamous cell carcinomas (OSCC) that have a serious impact on survival, including residual tumour and extracapsular spread. Moreover, other factors, including the lymph node ratio (LNR) and lymph node yield (LNY), have been suggested as prognostic markers.

Material and methods: This retrospective study included patients diagnosed with OSCC and cervical lymph node metastases during the years 2010-2020. Patients' records were evaluated regarding lymph node status, final therapy regime, tumour recurrence, time to death, tumour association with death, disease-free survival (DSF), and overall survival (OS).

Results: In 242 patients with a mean age of 63.57 ± 11.24 years, treated either by selective neck dissection (SND; n = 70) or by modified radical neck dissection (MRND; n = 172), 5772 lymph nodes were detected. The LNR and LNY were identified as independent risk factors in OS and DFS. The optimal cut-off point for the LNY was ≥ 17 lymph nodes in the SND and ≥ 27 lymph nodes in the MRND group. The metastatic lymph node clearance (MLNC) was established as a score to relate the LNR and LNY to the extent of lymph node removal. Survival analysis showed statistically significant differences among score levels.

Conclusions: As information about the extent of nodal dissection is excluded from LNR and LNY, we propose the use of a new scoring system comprising individual cut-off values for LNY and LNR with regard to the extent of neck dissection.

Clinical relevance: MLNC might help to identify high-risk OSCC patients with metastatic lymph nodes.

Keywords: Disease-free survival; Lymph node metastasis; Modified radical neck dissection; Oral squamous cell carcinoma; Overall survival; Selective neck dissection.

Fig. 1

Kaplan–Meier curves for disease-free survival (DFS; time in months) with regard to lymph node ratio (LNR): a selective neck dissection with a LNR threshold ≤ 0.06 and b modified radical neck dissection with a LNR threshold ≤ 0.12

Fig. 2

Kaplan–Meier curves for disease-free survival (time in months) with regard to lymph node yield (LNY): a selective neck dissection with a LNY threshold ≥ 17 and b modified radical neck dissection with a LNY threshold ≥ 27

Fig. 3

Kaplan–Meier curves for overall survival (OS; a) and disease-free survival (DFS; b) in groups regarding the metastatic lymph node clearance score (time in months)