Depth of invasion in early stage oral cavity squamous cell carcinoma: The optimal cut-off value for elective neck dissection.

Abstract

Depth of invasion (DOI) is the most important predictor for lymph node metastasis (LNM) in early stage (T1-T2) oral cancer. The aim of this study is to validate the cut-off value of 4mm on which the decision to perform an Elective Neck Dissection (END) is made. We performed a retrospective study in patients with pathologically proven early stage oral cavity squamous cell carcinoma (OCSCC) without clinical or radiological signs of LNM, who were treated between 2013 and 2018. An END was performed when DOI was≥4mm and a watchful waiting protocol was applied in patients with DOI<4mm. Three hundred patients were included. END was performed in 77% of patients with DOI≥4mm, of which 36% had occult LNM (pN+). Patients in the watchful waiting group (48%) developed a regional recurrence in 5.2% for DOI<4mm and 24.1% for DOI≥4mm. For DOI≥4mm, regional recurrence free survival was higher for patients who were treated with END compared to watchful waiting (p=0.002). A Receiver-Operator-Curve -analysis showed that a DOI cut-off value of 4.0mm was the optimal threshold for the prediction of occult LNM (95.1% sensitivity, 52.9% specificity). A DOI of≥4mm is an accurate cut-off value for performing an END in early stage OCSCC. END results in higher survival rates and lower regional recurrence rates in patients with DOI≥4mm.