Significance of Ki67, BCL 2 Immunoexpression in Urothelial Carcinoma and their Association with Grading and Staging: A Descriptive Cross-sectional Study

Abstract

Introduction: Urinary bladder is the most common site of malignancy in the urinary tract and the most common type of cancer of urothelial origin is urothelial cell carcinoma. This subtype constitutes more than 90% of bladder cancer. Histological grade of tumour is one of the most important predictive parameter for prognosis and biological behavior of urothelial carcinoma. As some crucial discordances may arise between pathologists because of subjectivity, so immunohistochemistry can be used for accurate diagnosis and prediction of prognosis. Aim: To study the immununohistochemical expression of B-Cell Lymphoma 2 (BCL 2) and Ki(Kiel)-67 markers and their association with tumour grade and stage in urothelial carcinomas. Materials and Methods: A descriptive cross-sectional study was conducted in the Department of Pathology of a tertiary care R G Kar Medical College and Hospital, Kolkata, West Bengal, India. West Bengal, India, on a total of 75 cases from January 2018 to June 2019. The study population comprised of cases of urothelial lesions as diagnosed by cystoscopy, who underwent standardized operative procedures. Relevant sections were taken from different parts of the fixed specimens. Histopathological Examination (HPE) was done to confirm the presence or absence of non-invasive and invasive carcinoma, and the depth of invasive tumour cells for pathological staging. Evaluation of the level of cytological and architectural disorder at low and medium magnification (100X and 200X) were done for grading. Cytological disorder were defined as abnormalities in nuclear size, shape, and chromatin, while architectural disorder were defined as abnormalities in the orientation of the cells in relation to each other and to the basement membrane of the papillae. Immunohistochemical analysis was done for Ki67 and BCL 2 expression in paraffin embedded sections in all the cases. In this study, chi-square test was done with International Business Management(IBM) Statistical Package for Social Sciences (SPSS), as per which, the association between two variables is statistically significant if p value is <0.05. Results: Out of total 75 cases(mean age: 67.3 years) analysed, 58 cases (77.3%) had Invasive type of bladder neoplasm, followed by low grade papillary urothelial carcinoma 10 (13.3%), and papillary urothelial neoplasm of low malignant potential 07 (9.3%). Ki67 expression in urothelial carcinoma has more significance because 59 cases (78.7%) showed high level expression (>20%) out of 75 cases, whereas only 12 (16%) cases show high level expression (4+) of BCL 2 marker. Conclusion: Ki67 overexpression is seen more commonly, than BCL 2, in high grade tumours as well as in advanced stage. So Ki67 may be used as a marker to predict aggressive behavior and to differentiate low grade and high grade tumours also.