Frequency of lymph node metastases at different neck levels in patients with oral squamous cell carcinoma: a systematic review and meta-analysis

Background: Currently, neck dissection is a standard treatment for the majority of oral squamous cell carcinoma (OSCC) patients. However, the procedure can lead to a series of complications, significantly reducing patient quality of life and even affecting the antitumor immune response in patients undergoing immunotherapy. Therefore, in the era of precision surgery, gaining a deeper understanding of the patterns of lymph node metastasis (LNM) in OSCC is crucial. Materials and methods: Literature searches were performed on PubMed, Embase, Web of Science, Cochrane Library, WANFANGDATA, and China National Knowledge Infrastructure (CNKI) (inception to 10 April 2024). In addition, a manual searching was conducted in Scopus, Google Scholar, and Education Resources Information Center (ERIC). The authors included observational studies that evaluated the frequency of LNM in OSCC patients. Systematic review and a random effects model meta-analysis were performed. Results: The search identified 4694 articles, of which 17 studies included in our study. The authors calculated the frequency of LNM according to the data reported in the articles. Frequency of LNM=number of patients with positive lymph node / number of patients with OSCC. The frequency of LNM was 12% in level I (95% CI: 0.11–0.15, I 2 =38.01%), 20% in level II (95% CI: 0.17–0.22, I 2 =47.71%), 10% in level III (95% CI: 0.08–0.12, I 2 =49.10%), 2% in level IV (95% CI: 0.01–0.03, I 2 =27.58%), 1% in level V (95% CI: 0.00–0.01, I 2 =11.37%). Conclusion: The frequency of LNM is consistent with the ‘cascade theory’ and appears to be no significant difference from different primary sites. The frequency of LNM were low in levels I–III and were very low in level IV–V, which implicated that more conservative treatments may be considered for OSCC in the future. This study will help clinicians better determine the extent of surgery and preserve lymph nodes during neck dissection.