P16 expression as a diagnostic parameter of endometrial carcinoma and endometrial hyperplasia

Abstract

Background: Endometrial cancer is malignant epithelial neoplasm originating from endometrium; endometrial cancer is the sixth most common cancer in women and the fifteenth most common cancer worldwide. The aim of study is to evaluate the expression of P16 IHC in endometrial carcinoma; and its diagnostic role in different histopathological types of endometrial carcinoma. Method: Retrospective study of 70 cases with collection of paraffin embedded tissue blocks and clinical data of patients with endometrial carcinoma and endometrial hyperplasia. H&E staining of slides done to confirm the histopathological diagnosis by specialist pathologist and then stained immunohistochemically for P16 marker. Results: In the current study, the average age of women was 32 to 78 years with a mean age of 53.42. More than half of the women with endometrial carcinoma (EC) (66.6%) presented in the age group between 50 and 70 years, half of the patients with atypical hyperplasia (50%) fall in the same age group as endometrial carcinoma, and the rest of the atypical hyperplasia patients and 65% of those without atypia presented in younger ages (30-50 years’ age group). (63.3%) of patients with endometrial cancer had postmenopausal bleeding; 70% of patients with atypical endometrial hyperplasia and 75% of those without atypia had excessive monthly bleeding (HMB). Histopathology correlated with patient age and clinical presentation. P16 immune marker expression did not correlate with stage at diagnosis of endometrial cancer in TAH & BSO instances. All endometrial serous carcinoma and more than half of EEC had positive p16 IHC. Endometrial hyperplasia had no P16 IHC expression, although more than half of endometrial cancer cases did. Conclusion: All endometrial serous carcinomas expressed high P16 IHC stain. More than half of endometrioid carcinomas had p16 IHC stain, with significant expression in high-grade morphological sections (FIGO 3). Most low-grade endometrioid carcinomas are P16-negative. P16 loss in all endometrial hyperplasia. P16 immunohistochemistry marker aids endometrial carcinoma diagnosis.