Clinical analysis of mediastinal lymph node dissection through sternotomy approach in the treatment of papillary thyroid carcinoma with mediastinal lymph node metastasis

Objective: To investigate the rule of mediastinal lymph node metastasis of papillary thyroid carcinoma and the application of therapeutic mediastinal lymph node dissection through the sternotomy approach in the treatment of mediastinal lymph node metastasis of papillary thyroid carcinoma. Methods: All cases of papillary thyroid carcinoma with mediastinal lymph node metastasis treated through sternotomy cooperated by thoracic surgeons and head and neck surgeons from January 2006 to January 2017 in Cancer Hospital of Chinese Academy of Medical Sciences were included in this study. The distribution, metastasis rate, metastasis degree, surgical method, surgical complications and postoperative survival of patients with mediastinal lymph node metastasis were retrospectively analyzed. Results: A total of 31 patients (16 males and 15 females) with papillary thyroid cancer with mediastinal lymph node metastasis, with a median age of 46 (19-65) years, were enrolled in the group. Partial upper sternotomy was used in 28 cases, and total sternotomy was used in 3 cases. The mediastinal lymph nodes of papillary thyroid carcinoma metastasized farthest to the station 6, and the lymph node metastasis rate of each group from high to low was: 2R (61%), 1R (39%), 3A (39%), 1L (16%), 2L (10%), 4R (10%), 5 (3%) and 6 (3%). No metastasis was observed in station 3P, 4L and 7. In addition, the degree of lymph node metastasis at station 2R was the highest, reaching 35% (77/219). Extra-nodal invasion of mediastinal metastatic lymph nodes in thyroid papillary carcinoma is common (23%), easily fuses into masses (23%) and invades peripheral vascular nerves (26%). Up to 29% of blood transfusions are required during or after surgery due to oozing or bleeding (9/31). The 1-, 3-, 5-and 10-year survival rates of patients undergoing surgical treatment were 94%, 94%, 87% and 81%, respectively. Conclusion: Papillary thyroid carcinoma can metastasize to almost all mediastinal lymph nodes except station 3P, 4L and 7. Radical mediastinal lymph node dissection through sternotomy is an effective method for the treatment of mediastinal lymph node metastasis of thyroid papillary carcinoma.