Lymph node ratio (LNR) and lymph node yield (LNY) in head and neck cancer: A systematic review and meta-analysis.

Introduction: A growing amount of evidence points at lymph node yield (LNY) and lymph node ratio (LNR) as useful indicators in the prognostic evaluation of patients affected by head and neck squamous cell carcinoma (HNSCC) who require neck dissection. The aim of this study was to assess the importance of LNY and LNR in the prognostic evaluation of head and neck cancer patients.

Materials And Methods: Included studies were those examining LNY and/or LNR in head and neck cancer patients. We excluded case reports or case series, thyroid cancer or salivary gland cancer studies, a sample size less than 20, and studies with incomplete or missing survival estimate. Of the 2435 studies identified through a database search, 95 were reviewed for full text and 63 were finally included for the final analysis. Electronic databases, including PubMed (MEDLINE), Embase, and Scopus were screened up to January 1, 2024. The systematic review was conducted according to the MOOSE checklist. A set of sub-group meta-analyses were performed for oral cavity, oropharynx, hypopharynx, larynx, and mixed subsites using a random-effects model. Overall survival (OS), Disease Specific Survival (DSS), and Disease-Free Survival (DFS) Hazard Ratios (HR) related to a prespecified LNR and LNY exact value were chosen as summary statistics. Cumulative Hazard Ratios with 95% Confidence Interval (CI) were presented, calculated through the inverse variance method. Heterogeneity was evaluated with I statistics.

Results: Results of the meta-analysis showed increased OS for a higher LNY (HR 1.33 95% CI 1.23-1.45). Regarding the LNR, a lower LNR value has an impact on survival, with an OS HR of 1.96 (95% CI 1.72-2.24). The same was true for DFS (HR 2.43 95% CI 1.82-3.23), and DSS (HR 2.07 95% CI 1.83-2.33).

Conclusions: Our analysis confirms the importance of LNY and LNR as prognostic indicators. Future studies are needed to establish the optimal cut-off values for both factors. LNY and LNR have the potential to be routinely evaluated in patients who undergo neck dissection for HNSCC.