Depth of invasion determined by MRI in cT1N0 tongue: is it an indicator for elective neck dissection?

Abstracts Background Depth of invasion (DOI) could be calculated by MRI preoperatively, whether MRI-determined DOI could predict the prognosis and whether it could be used as an indicator for neck dissection for cT1N0 tongue squamous cell carcinoma (SCC) remain unknown, the main goal of the current study aimed to answer the questions. Methods Patients with surgically treated cT1N0 tongue SCC were retrospectively enrolled, MRI-determined DOI was measured based on T1-weigthed layers by a 1.5T scan. A multivariate logistic regression analysis model was used to determine the independent predictors for occult neck lymph node metastasis. The main study endpoints were locoregional control survival (LRC) and disease specific survival (DSS), the Cox model was used to determine the independent prognostic factors for the LRC and DSS. Results Occult neck lymph node metastasis was noted in 26 (17.2%) patients, ROC curve indicated the optimal cutoff value of MRI-determined DOI was 7.5mm for predicting neck lymph node metastasis with sensitivity of 86.9%. The factors of lymphovascular invasion, MRI-determined DOI, pathologic DOI, and pathologic tumor grade were significantly associated with the presence of neck lymph node metastasis in univariate analysis, further logistic regression analysis confirmed the independence of lymphovascular invasion, MRI-determined DOI, and pathologic DOI in predicting the neck lymph node metastasis. The 5-year LRC and DSS rates were 84% and 90%, respectively. Cox model analysis suggested the MRI-determined DOI was an independent prognostic factor for both the LRC and DSS. Conclusions Elective neck dissection is suggested if MRI-determined DOI is greater than 7.5mm in cT1N0 tongue SCC, and MRI-determined DOI ≥7.5mm indicates more risk for disease recurrence and cancer caused death.