[Research progress in diagnosis and treatment of salivary gland tumors]

Salivary gland tumor is one of the most common tumors in oral and maxillofacial regions. The diagnosis and treatment of salivary gland tumors had been a clinical characteristic project in Peking University School and Hospital of Stomatology since long time ago. Here we introduced the research progress in diagnosis and treatment of salivary gland tumors during the past 10 years. Among 7 190 cases of salivary gland tumors treated in this institution, 4 654 cases (64.7%) were benign, and 2 536 (35.3%) were malignant, with benign ∶ malignant ratio of 1.84 ∶ 1. Parotid was the most common location, followed by minor salivary gland and submandibular gland, while sublingular gland tumor was seldom seen. The proportion of minor salivary gland tumor was relatively high. Among 1 874 cases with primary malignant tumors, the cases with T3 and stage Ⅲ accounted for only 9.6% and 10.3%, respectively, which indicated that there was shortcoming in the T classification and clinical stage formulated by Union for International Cancer Control (UICC), and further revision was required. The 5, 10, and 15 year survival rates of 1 637 cases with postoperative follow-up were 93.1%, 87.2% and 79.3%, respectively, which were much higher than those we reported 30 years ago. The improvement of treatment results was related to more widely used combined treatment with surgery and postoperative radiotherapy, and the increase in patients with early stage. Adenoid cystic carcinoma was the malignant tumor with high rate of distant metastasis. The 5 and 10 year survival rates of the patients with pulmonary metastasis were 76.2% and 51.8%, respectively, which indicated that the pulmonary metastatic carcinomas developed slowly. Recurrent rate of carcinoma ex pleomorphic adenoma was 46.7% after single treatment of sur-gery, while it decreased to 27.5% after combined theraphy with surgery and radiotherapy, indicating that postoperative radiotheraphy could reduce the recurrent rate effectively. The normal myoepithelial cells had the inhibiting role in the invasion and metastasis of carcinoma ex pleomorphic adenoma. The evaluation of integrity of myoepithelial cells surrounding the tumor mass is helpful to understand the invasiveness of the tumors. The new surgical modalities such as extracapsular resection and partial sialoadenectomy were used in treatment of benign tumors of parotid gland and submandibular gland with advantages of decreased tissue damage and preservation of glandular function. Application of digital surgical techniques such as mixed reality combined with surgical navigation and real-time three-dimensional holograms in the surgical treatment of parotid gland tumors showed the benifits of more safety and precision, and less tissue da-mage.