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

Abstract

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, 1 undifferentiated carcinoma, and 1 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.