Depth of Invasion in Early Oral Cancer: Is 4MM a Threshold for Elective Neck Dissection?

Lymph node metastasis is one of the most important prognostic factors in oral squamous cell carcinoma. In early stage oral cancers, Depth of invasion (DOI) is a predictor for lymph node metastasis. The aim of this study was to evaluate if DOI 4 mm can be considered as a threshold for clinical decision making on elective neck dissection (END) in early oral cancer, by assessing the association of DOI and the risk of occult lymph node metastasis in early Oral squamous cell carcinoma (OSCC). A retrospective study was conducted on 319 patients with early pT1-2 OSCC who were clinically N negative. All patients underwent primary resection and END. The patients were divided into two groups based on DOI: < 4 mm and ≥ 4 mm. Nodal metastases were then noted for each group. The rate of nodal metastasis in respect to tumor size was also observed. Out of 111 patients having DOI < 4 mm only 15 (4.7%) had lymph node metastasis, whereas out of 208 patients having DOI ≥ 4 mm, 81 patients (25.4%) had neck node metastasis, with p value < 0.05. Tumors having DOI ≥ 4 mm has higher chances of occult metastasis and also increased probability of other prognostic factors like PNI and LVI, suggesting that DOI ≥ 4 mm can be considered a cut - off value for performing END.