부산대학교 도서관

AimsThe aim of the study is to correlate p16Ink4aexpression with the clinical courses of pleomorphic adenoma (PA), its malignant transformation (CaexPA) and treatment outcomes.MethodsRetrospective analysis (1998–2019) of 47 CaexPA, 148 PA and 22 normal salivary gland samples was performed. PAs were divided into two subsets: clinically ‘slow’ tumours characterised by stable size or slow growth; and ‘fast’ tumours with rapid growth rate.ResultsPositive p16Ink4aexpression was found in 68 PA and 23 CaexPA, and borderline expression in 80 and 20, respectively. All 22 (100%) normal salivary gland samples presented with no p16Ink4aexpression. Significant difference in p16Ink4aexpression was observed between normal tissue, PA and CaexPA (χ2(4)=172,19; p=0.0001). The PA clinical subgroups were also evaluated separately, revealing additional statistical relations: ‘fast’ PA and CaexPA differed significantly in p16Ink4a expression (χ2(2)=8.06; p=0.01781) while ‘slow’ PA and CaexPA did not (χ2(2)=3.09; p=0.2129). 3-year, 5-year and 10-year survival among p16Ink4apositive CaexPA patients was 100%, 90.56% and 60.37%, respectively, and in CaexPA patients with borderline p16Ink4aexpression was 90.0%, 73.64% and 22.20%, respectively. Statistically significant difference between expression pattern and survival rate was observed (F Cox test – F (16, 24)=2.31; p=0.03075).ConclusionsOur study confirms no p16Ink4aexpression in normal tissue, but reveals differences in expression between ‘fast’ and ‘slow’ PA. We suggest that p16Ink4aoverexpression is connected to PA proliferation and subsequent malignant transformation to CaexPA. Borderline p16Ink4astaining correlates with worse prognosis of CaexPA.