Immunoexpression of HER2/Neu and Ki-67 in Gastrointestinal Carcinomas and their Association with Histomorphological Parameters: A Cross-sectional Study

Introduction: Gastrointestinal (GI) malignancies have been considered as one of the leading causes of deaths worldwide lately. Personalised cancer therapy is an emerging approach for tumour treatment currently as treatment is chosen based on tumour genomics. Over expression of HER2/Neu has been identified in these tumours particularly in gastric and colonic carcinomas and availability of anti-HER2 monoclonal antibody can serve as an effective tool to improve the survival outcomes in these patients. Aim: To analyse the expression of HER2/Neu and Ki-67 in GI carcinomas. Materials and Methods: The presentdescriptive cross-sectional study was conducted for a period of one year from July 2023 to June 2024 in the Department of Pathology, Hind Institute of Medical Sciences, Barabanki, Uttar Pradesh, India. Out of 67 GI specimens received during the study period, a total of 50 cases of GI carcinomas were included. All relevant clinicopathological data were obtained from patient’s medical record file. Histopathological examination and Immunohistochemistry (IHC) using HER2/Neu and Ki-67 biomarkers was performed and their association with various histomorphological parameters including tumour type, grade, lymphovascular and perineural invasion and lymph node status was assessed. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) Statistics version 28.0. Pearson Chisquare or Fisher-exact test was used to detect the association between histopathological features and HER2/Neu and Ki-67 expression status. Results: Positive HER2/Neu expression was seen in 14 (28%) of the cases while high Ki-67 index was observed in 29 (58%) of the cases. Positive Her2 expression was more common in Gastric adenocarcinoma (n=40; 6%) as compared to other sites. Most well differentiated (n=10/28; 35.71%) tumours showed strong HER2/Neu positivity. Although most HER2/Neu positive cases (n=13/14; 92.85%) showed high Ki-67 index, Ki67 independently did not show any significant association with other morphological parameters. Conclusion: The study recommends use of both HER2/Neu and Ki-67 index in GI carcinomas as their expression and association can provide a comprehensive data of a specific tumour type stemming in different sites of GI tract.