[Characteristics of cervical lymph node metastasis of cN0 laryngeal carcinoma]

Objective: To investigate the incidence of occult cervical lymph node metastasis and the common neck level of metastases in cN0 laryngocarcinoma, and the relationship between the clinicopathologic features of laryngocarcinoma and cervical lymph node metastasis. Methods: A total of 506 cases with cN0 laryngocarcinoma treated at the First Affiliated Hospital of Chongqing Medical University between March 2011 and March 2018 were enrolled, and their medical records and follow-up data were retrospectively analyzed. Of them, 211 cases of were glottic carcinoma in stage T1 without neck dissection and they were observed by clinical follow-up; other 295 cases, including glottic carcinoma, supraglottic carcinoma and hypopharyngeal carcinoma in stage T2-T4 were treated with surgical resection of the primary lesions and selective neck dissection. SPSS 22.0 software was used to analyze the data. Results: The total incidence of cervical lymph node metastasis was 10.87%(55/506), with a lower incidence in T1 stage glottic carcinoma(6/211,2.84%) than that in other cases(49/295,16.61%). The incidence of cervical lymph node metastasis in glottic carcinoma (29/426, 6.81%) was lower than those in supraglottic carcinoma (22/71,30.99%) and subglottic carcinoma (4/9) (χ(2)=35.810,P<0.01).The pN+ rates of glottic carcinoma at T1, T2, T3 were 2.84%(6/211), 5.31%(6/113), 16.05%(13/81), and 19.05%(4/21), respectively (χ(2)=18.572, P<0.01). The pN+ rates of supraglottic carcinoma at T2, T3 and T4 were 3/13, 32.50%(13/40) and 6/13, respectively (χ(2)=3.649,P>0.05). The incidence of cervical lymph node metastasis in poorly differentiated carcinoma (17/42, 40.48%) was higher than those in moderately differentiated carcinoma (26/205, 12.68%) and high differentiated carcinoma(12/246, 4.88%)(χ(2)=36.356, P<0.01). Moreover, 85 pN+ lymph nodes were obtained by selective neck dissection, respectively 43(50.59%) in level Ⅱa, 30(35.29%) in level Ⅲ, 1(1.18%) in level Ⅳ and 11(12.94%) in level Ⅵ. Conclusions: The occult cervical lymph node metastasis was frequently found in cN0 laryngocarcinoma. Selective neck dissection should be performed with surgery for the primary lesions in T3-T4 glottic laryngeal cancer, T2-T4 supraglottic laryngeal cancer and subglottic carcinoma, and the neck dissection for level Ⅱa and Ⅲ is appropriate. It is required to detect pre-laryngeal and pre-tracheal lymph nodes in patients with subglottic laryngeal carcinoma.