Background: Pleomorphic adenoma accounts for the majority of benign tumors of the salivary gland. It is also called mixed tumor because it is composed by ductal epithelial and myoepithelial cells, variably intermixed within a chondromyxoid stroma. The recurrence rate is around 3.4% and 6.3%, respectively at 5 and 10 years and, to date, there are no valuable predictive factors. Aim of our study was to assess the role of Ki67 proliferative index in our cases and through meta-analysis.
Methods: Immunohistochemistry with Ki67 antibody was performed on 28 cases. A manual count of the signal was performed, to establish the proliferative activity. Statistical tests were applied to assess the correlation between the score and clinico-pathologic parameters. Further data were extrapolated from studies published on Pubmed, Cochrane and Web of Science database.
Results: Higher values of Ki67 were found among cases with larger size (p value = 0.0061) and showing greater cellularity (p value=0.0004). 19 papers were selected from the bibliographic search, concerning a total of 1187 patients affected by pleomorphic adenoma. In most of them, a higher Ki67 was detected among relapsing forms but results were controversial. In each study, several count methods were applied.
Conclusion: The role of Ki67 in pleomorphic adenoma of the salivary glands remains unclear. The lack of homogeneity of the data makes it very difficult to standardize them in order to draw a conclusion. It would therefore be desirable to carry out a comparison study of the various possible methods of Ki67 counting.
Keywords: Ki-67; Ki67; Pleomorphic adenoma; Prognosis; Proliferation.
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