Ki-67 Proliferation Rate as a Prognostic Marker in Major Salivary Gland Carcinomas

Objectives: The study was performed to evaluate the prognostic relevance of cell proliferation associated with Ki-67/Mib-1 immunostaining in malignant tumors of the major salivary glands. Methods: Cell proliferation was evaluated by Mib-1 antibody against Ki-67 antigen in 41 patients with cancer of the parotid or submandibular glands, including 14 acinic cell carcinomas, 12 ductal carcinomas, 7 mucoepidermoid carcinomas, 5 carcinomas ex pleomorphic adenoma, 1 adenoid cystic carcinoma, I undifferentiated carcinoma, and I polymorphous low-grade adenocarcinoma. Results: Patients with Ki-67 values of more than 15% and those with Ki-67 values of 15% or less differed both in disease-free survival (p < 0.001) and in overall survival (p < 0.001). We evaluated the association between Ki-67 and time to recurrence in correlation to age, sex, ductal histotype, and N stage; the Cox regression model was significant (p = 0.013). In the group of patients with T1 and T2 cancers, those with Ki-67 values of 15% or less had better survival rates than did those with Ki-67 values of more than 15% (p = 0.004). In the group of patients with NO cancers, those with Ki-67 values of 15% or less had a better survival than did those with Ki-67 values of more than 15% (p < 0.001). Conclusions: To our knowledge, this is the first study to stratify different risk classes in early T1-T2 or NO malignant tumors of the major salivary glands that identified aggressive lesions with elevated Ki-67 expression at an initial stage.