ABSTRACT
Depth of invasion is a newly added index for TNM staging of oral cancer in the eighth edition. Preoperative evaluation of depth of invasion not only provides a reference for surgical margin, but also serves as an independent prognostic factor for predicting lymph node metastases. At present, the main methods for assessing the depth of invasion of tongue squamous cell carcinoma include ultrasound examination, MRI, CT, positron emission tomography (PET) and histopathological examination. This paper summarizes the evaluation method and clinical effect of depth of invasion of tongue cancer, and analyzes its advantages and boundedness. In addition, this study is expected to provide a reference for the surgical treatment of tongue squamous cell carcinoma.