Clinical study on the pattern of lower-level lymphatic metastasis in primary tongue squamous cell carcinoma

To study and analyze the clinical patterns of lower-level lymph node (Ⅳ and Ⅴ) metastasis in primary tongue squamous cell carcinoma, and establish a reference for the decision-making of the lower-level neck dissection in tongue squamous cell carcinoma.

A total of 203 patients with primary tongue squamous cell carcinoma were recruited. These patients underwent simultaneous/secondary comprehensive neck (level Ⅰ-Ⅴ) dissection in Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from January 2010 to December 2015. Their clinicopathological and follow-up data were obtained and analyzed to reveal the prognosis and risk factors of primary tongue squamous cell carcinoma with lower-level lymph node metastasis.

Among the 203 patients, the metastasis rates of levels Ⅳ and Ⅴ are 14.78% and 4.93%, respectively. Level Ⅳ metastasis is more prevalent in males than females (P=0.04); non-smokers are more likely to have level Ⅴ metastasis than smokers (P=0.046). Lymph node status in levels Ⅲ and Ⅳ are significantly associated with the risk of metastasis in level Ⅴ (P=0.001). Patients with extracapsular invasion in level Ⅲ have a significantly increased risk of metastasis in levels Ⅳ (P=0.014) and Ⅴ (P=0.026). The 5-year survival rate of patients with lower lymph node (Ⅳ/Ⅴ) metastasis is only 14.70%, which is an independent poor prognostic factor for patients with primary tongue squamous cell carcinoma (P<0.000 1).

Most primary tongue squamous cell carcinoma metastases occur in levels Ⅰ-Ⅲ. However, the rate of lower-level lymph node metastasis is rather low. For the cN0 and cN+ patients with levels Ⅰ-Ⅱ lymph node metastases without extracapsular invasion, the strategy for level Ⅴ management may be observation rather than dissection.